diff --git a/.travis.yml b/.travis.yml
index ac31b01a0..ab312037b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,4 @@
 language: node_js
 node_js: 10
 script:
-- npm run-script build
-- npm test
-- npm run-script check-format
+- make lint build test check-format
diff --git a/Gruntfile.js b/Gruntfile.js
index daf5f8174..d56e77379 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -32,9 +32,9 @@ module.exports = function(grunt){
       options: {
         banner: banner_full,
         process: true,
-	  },
+      },
       pzpr: {
-        options: {
+        options:{
           sourceMap: !PRODUCTION
         },
         files: [
@@ -56,16 +56,6 @@ module.exports = function(grunt){
         banner: banner_min,
         report: 'min'
       },
-      pzpr:{
-        options: (PRODUCTION ? {} : {
-          sourceMap : 'dist/js/pzpr.js.map',
-          sourceMapIn : 'dist/js/pzpr.concat.js.map',
-          sourceMapIncludeSources : true
-        }),
-        files: [
-          { src: 'dist/js/pzpr.concat.js', dest: 'dist/js/pzpr.js'}
-        ]
-      },
       variety:{
         options: (PRODUCTION ? {} : {
           sourceMap : function(filename){ return filename+'.map';}
@@ -96,10 +86,7 @@ module.exports = function(grunt){
     }
   });
   
-  grunt.registerTask('default', ['build']);
-  grunt.registerTask('release', ['build']);
-  grunt.registerTask('build',        ['build:pzpr', 'build:variety', 'build:samples', 'build:ui']);
-  grunt.registerTask('build:pzpr',   ['newer:concat:pzpr', 'newer:uglify:pzpr']);
+  grunt.registerTask('build',        ['build:variety', 'build:samples', 'build:ui']);
   grunt.registerTask('build:ui',     ['newer:copy:ui', 'newer:concat:ui', 'newer:uglify:ui']);
   grunt.registerTask('build:variety',['newer:uglify:variety']);
   grunt.registerTask('build:samples',['newer:uglify:samples']);
diff --git a/Makefile b/Makefile
index ea3c750c3..9ef07d398 100644
--- a/Makefile
+++ b/Makefile
@@ -1,10 +1,31 @@
-.PHONY: build test serve format
+.PHONY: default build test serve serve-all format check-format lint bundle rollup git-hash clean
 
-build:
-	npm run-script build
+default: build
 
-test:
-	npm test
+clean:
+	rm -rf ./dist/
+	rm -f git.json
+
+build: rollup git-hash
+	npx grunt build
+
+git-hash:
+	./git-hash.sh
+
+bundle: git-hash
+	npx grunt concat:pzpr
+
+rollup: bundle
+	mkdir -p ./dist/js/
+	cp ./node_modules/pzpr-canvas/dist/candle.js ./dist/js/candle.js
+	npx rollup -c ./rollup.config.js
+
+test: bundle
+	npx grunt build:variety
+	npx mocha -r esm -r pzpr-canvas -r source-map-support/register -R progress --recursive test
+
+lint:
+	npx eslint --quiet src src-ui test sample
 
 serve:
 	cd dist && python3 -m http.server -b localhost
@@ -13,4 +34,7 @@ serve-all:
 	cd dist && python3 -m http.server
 
 format:
-	npm run-script format
+	npx prettier --write "{src,src-ui,test}/**/*.{js,json,css}"
+
+check-format:
+	npx prettier --check "{src,src-ui,test}/**/*.{js,json,css}"
diff --git a/index.js b/index.js
index fdf94cc63..62223b47a 100644
--- a/index.js
+++ b/index.js
@@ -1,2 +1,3 @@
 
-module.exports = require('./dist/js/pzpr.js');
+import pzpr from './dist/js/pzpr.concat.js';
+export default pzpr;
diff --git a/package.json b/package.json
index bbaa3a9d5..e6150ad97 100644
--- a/package.json
+++ b/package.json
@@ -3,9 +3,6 @@
   "version": "0.12.0",
   "description": "Scripts for handling puzzle objects",
   "main": "./index.js",
-  "directories": {
-    "test": "test"
-  },
   "keywords": [
     "puzzle",
     "HTML5"
@@ -14,35 +11,24 @@
   "license": "MIT",
   "repository": {
     "type": "git",
-    "url": "https://github.com/sabo2/pzprjs"
-  },
-  "homepage": "https://github.com/sabo2/pzprjs",
-  "engines": {
-    "node": ">= 5.6.0"
-  },
-  "scripts": {
-    "build": "eslint --cache --quiet src src-ui && \"./git-hash.sh\" && grunt default",
-    "release": "npm run clean && eslint --cache --quiet src && grunt release",
-    "clean": "del dist/* pzpr-*.{zip,tar.gz,tar.bz2,tgz}",
-    "format": "prettier --write \"{src,src-ui,test}/**/*.{js,css}\"",
-    "check-format": "prettier --check \"{src,src-ui,test}/**/*.{js,css}\"",
-    "lint": "eslint src src-ui test sample",
-    "test": "eslint --quiet src src-ui test sample && mocha -r source-map-support/register -R progress --recursive test",
-    "prepublishOnly": "npm test"
+    "url": "https://github.com/robx/pzprjs"
   },
+  "homepage": "https://puzz.link",
   "devDependencies": {
-    "del-cli": "^2.0.0",
     "eslint": "^5.16.0",
+    "esm": "^3.2.25",
     "grunt": "^1.1.0",
     "grunt-contrib-concat": "^1.0.1",
     "grunt-contrib-copy": "^1.0.0",
     "grunt-contrib-uglify": "^2.0.0",
     "grunt-newer": "^1.1.1",
     "mocha": "^6.2.3",
-    "prettier": "^1.19.1"
+    "prettier": "^1.19.1",
+    "rollup": "^2.8.0",
+    "rollup-plugin-terser": "^5.3.0"
   },
   "dependencies": {
     "pzpr-canvas": "^0.8.2",
-    "source-map-support": "^0.5.17"
+    "source-map-support": "^0.5.19"
   }
 }
diff --git a/rollup.config.js b/rollup.config.js
new file mode 100644
index 000000000..f371a0ae1
--- /dev/null
+++ b/rollup.config.js
@@ -0,0 +1,22 @@
+import { terser } from 'rollup-plugin-terser';
+
+// `npm run build` -> `production` is true
+// `npm run dev` -> `production` is false
+const production = !process.env.ROLLUP_WATCH;
+
+export default {
+	input: 'dist/js/pzpr.concat.js',
+	output: {
+		file: 'dist/js/pzpr.js',
+		name: 'pzpr',
+		format: 'iife',
+		sourcemap: true,
+		globals: {
+			"pzpr-canvas": "Candle"
+		}
+	},
+	context: "window",
+	plugins: [
+		production && terser() // minify, but only in production
+	]
+};
diff --git a/src-ui/list.html b/src-ui/list.html
index ca78aaacb..9f0cef969 100644
--- a/src-ui/list.html
+++ b/src-ui/list.html
@@ -5,6 +5,7 @@
 <meta http-equiv="Content-Type" content="text/html">
 <TITLE>puzz.link list of puzzle types</TITLE>
 <link rel="stylesheet" href="./css/list.css?<%= git.hash %>">
+<script src="./js/candle.js?<%= git.hash %>"></script>
 <script src="./js/pzpr.js?<%= git.hash %>"></script>
 <script src="./js/list.js?<%= git.hash %>"></script>
 </HEAD>
diff --git a/src-ui/p.html b/src-ui/p.html
index ca2e350b8..0a7a06efa 100644
--- a/src-ui/p.html
+++ b/src-ui/p.html
@@ -11,6 +11,7 @@
 <link rel="mask-icon" href="./safari-pinned-tab.svg" color="#5bbad5">
 
 <link rel="stylesheet" href="./css/ui.css?<%= git.hash %>" type="text/css">
+<script type="text/javascript" src="./js/candle.js?<%= git.hash %>"></script>
 <script type="text/javascript" src="./js/pzpr.js?<%= git.hash %>"></script>
 <script type="text/javascript" src="./js/pzpr-ui.js?<%= git.hash %>"></script>
 <title>puzz.link player</title>
diff --git a/src-ui/rules.html b/src-ui/rules.html
index f10b430a1..ea91443bc 100644
--- a/src-ui/rules.html
+++ b/src-ui/rules.html
@@ -39,6 +39,7 @@
 }
 </style>
 
+<script type="text/javascript" src="./js/candle.js?<%= git.hash %>"></script>
 <script type="text/javascript" src="./js/pzpr.js?<%= git.hash %>"></script>
 <script>
 
diff --git a/src/.eslintrc.json b/src/.eslintrc.json
index 1d6d6e300..d381a0403 100644
--- a/src/.eslintrc.json
+++ b/src/.eslintrc.json
@@ -1,34 +1,35 @@
 {
   "env": {
-    "browser": true,                    // Allow to use browser defined variable (not console, alert etc.)
-    "node": true                        // Allow to use node defined variable (require, process etc.)
+    "browser": true, // Allow to use browser defined variable (not console, alert etc.)
+    "node": true // Allow to use node defined variable (require, process etc.)
   },
   "parserOptions": {
-    "ecmaVersion": 5
+    "ecmaVersion": 5,
+    "sourceType": "module"
   },
   "globals": {
     "pzpr": "readonly"
   },
-  "extends": "eslint:recommended",      // Implement recommended rules
+  "extends": "eslint:recommended", // Implement recommended rules
   "rules": {
-    "curly": ["error", "all"],          // Error for no curly brancket in loop or conditions
-    "no-unused-vars":                   // Error for unused variables, not detect arguments
-        ["error", {"args": "none"}],
-    "no-undef": "error",                // Error for unused variable (that will become global variable)
-    "new-cap": "error",                 // Error for lowercase first letter or constructor call as function
-    "eqeqeq": ["error", "always"],      // Error for ==, != to compare
-    "no-use-before-define":             // Error for using variable before definition
-        ["error", {"functions":false, "classes":false}],
+    "curly": ["error", "all"], // Error for no curly brancket in loop or conditions
+    // Error for unused variables, not detect arguments
+    "no-unused-vars": ["error", { "args": "none" }],
+    "no-undef": "error", // Error for unused variable (that will become global variable)
+    "new-cap": "error", // Error for lowercase first letter or constructor call as function
+    "eqeqeq": ["error", "always"], // Error for ==, != to compare
+    // Error for using variable before definition
+    "no-use-before-define": ["error", { "functions": false, "classes": false }],
     "comma-dangle": ["error", "never"], // Error for trailing comma
-    "no-redeclare": "warn",             // Warn redefine variable (TODO: make this rule error)
+    "no-redeclare": "warn", // Warn redefine variable (TODO: make this rule error)
     //"block-scoped-var": "warn",       // Warn var declaration inside block scope
-    "no-empty": "off",                  // Allow empty block statements
-    "no-constant-condition":            // Allow constant condition in conditions
-        ["error", {"checkLoops": false}],
-    "no-useless-escape": "off",         // Allow unnessesary escape charactors
-    "no-extra-boolean-cast": "off",     // Allow to use boolean cast for boolean value
-    "no-mixed-spaces-and-tabs": "off",  // Allow to use spaces and tabs for indent
-    "dot-notation": "off",              // Allow object access via obj["name"]
-    "no-loop-func": "off"               // Allow function definition in loop
+    "no-empty": "off", // Allow empty block statements
+    // Allow constant condition in conditions
+    "no-constant-condition": ["error", { "checkLoops": false }],
+    "no-useless-escape": "off", // Allow unnessesary escape charactors
+    "no-extra-boolean-cast": "off", // Allow to use boolean cast for boolean value
+    "no-mixed-spaces-and-tabs": "off", // Allow to use spaces and tabs for indent
+    "dot-notation": "off", // Allow object access via obj["name"]
+    "no-loop-func": "off" // Allow function definition in loop
   }
 }
diff --git a/src/common/intro.js b/src/common/intro.js
deleted file mode 100644
index 29d249881..000000000
--- a/src/common/intro.js
+++ /dev/null
@@ -1,3 +0,0 @@
-// intro.js
-
-(function(){
diff --git a/src/common/outro.js b/src/common/outro.js
deleted file mode 100644
index bf0df2f87..000000000
--- a/src/common/outro.js
+++ /dev/null
@@ -1,3 +0,0 @@
-// outro.js
-
-})();
diff --git a/src/header.js b/src/header.js
new file mode 100644
index 000000000..49e2cbe5d
--- /dev/null
+++ b/src/header.js
@@ -0,0 +1,14 @@
+var pzpr = {
+	version: "<%= git.hash %>"
+};
+export default pzpr;
+
+import Candle from "pzpr-canvas";
+pzpr.Candle = Candle;
+
+//eslint-disable-next-line no-unused-vars
+var document = this.document || pzpr.Candle.document;
+//eslint-disable-next-line no-unused-vars
+var DOMParser = this.DOMParser || pzpr.Candle.DOMParser;
+//eslint-disable-next-line no-unused-vars
+var XMLSerializer = this.XMLSerializer || pzpr.Candle.XMLSerializer;
diff --git a/src/lib/candle-intro.js b/src/lib/candle-intro.js
deleted file mode 100644
index 06d750e89..000000000
--- a/src/lib/candle-intro.js
+++ /dev/null
@@ -1,13 +0,0 @@
-// candle-intro.js
-
-(function(){
-
-
-//---------------------------------------------------------------------------
-// node.js環境向けの対策
-//---------------------------------------------------------------------------
-var document = this.document;
-
-var module = {exports:{}}, exports = module.exports;
-
-(function(module,exports){
diff --git a/src/lib/candle-outro.js b/src/lib/candle-outro.js
deleted file mode 100644
index a5e744a70..000000000
--- a/src/lib/candle-outro.js
+++ /dev/null
@@ -1,14 +0,0 @@
-// candle-outro.js
-
-})(module,exports);
-
-pzpr.Candle = module.exports;
-
-})();
-
-//---------------------------------------------------------------------------
-// node.js環境向けの対策
-//---------------------------------------------------------------------------
-    document      = this.document      || pzpr.Candle.document;
-var DOMParser     = this.DOMParser     || pzpr.Candle.DOMParser;
-var XMLSerializer = this.XMLSerializer || pzpr.Candle.XMLSerializer;
diff --git a/src/pzpr.js b/src/pzpr.js
index d50625f96..e43d6d84a 100644
--- a/src/pzpr.js
+++ b/src/pzpr.js
@@ -1,9 +1,5 @@
 exports.files = [
-	"common/intro",
-	"pzpr/core",
-	"lib/candle-intro",
-	"../node_modules/pzpr-canvas/dist/candle",
-	"lib/candle-outro",
+	"header",
 	"pzpr/env",
 	"pzpr/event",
 	"pzpr/classmgr",
@@ -34,8 +30,7 @@ exports.files = [
 	"variety-common/Answer",
 	"variety-common/BoardExec",
 	"variety-common/Encode",
-	"variety-common/FileData",
-	"common/outro"
+	"variety-common/FileData"
 ].map(function(mod) {
 	return "src/" + mod + ".js";
 });
diff --git a/src/pzpr/core.js b/src/pzpr/core.js
deleted file mode 100644
index e782f36d9..000000000
--- a/src/pzpr/core.js
+++ /dev/null
@@ -1,15 +0,0 @@
-// core.js v3.5.2
-
-//----------------------------------------------------------------------------
-// ★pzprオブジェクト
-//---------------------------------------------------------------------------
-/* extern */
-var pzpr = {
-	version: "<%= git.hash %>"
-};
-
-if (typeof module === "object" && module.exports) {
-	module.exports = pzpr;
-} else {
-	this.pzpr = pzpr;
-}
diff --git a/src/pzpr/util.js b/src/pzpr/util.js
index 0f83adc36..1a2ed80f4 100644
--- a/src/pzpr/util.js
+++ b/src/pzpr/util.js
@@ -46,11 +46,7 @@
 					}
 				}
 			} else {
-				return (
-					require("path").dirname(__filename) +
-					"/" +
-					(__filename.match("pzpr.js") ? "" : "../")
-				);
+				return require("path").dirname(__filename) + "/";
 			}
 			return "";
 		},
diff --git a/src/variety/tawa.js b/src/variety/tawa.js
index 21e76fa08..82ccba445 100644
--- a/src/variety/tawa.js
+++ b/src/variety/tawa.js
@@ -84,7 +84,20 @@
 		numberRemainsUnshaded: true,
 
 		maxnum: 6,
-		minnum: 0
+		minnum: 0,
+
+		adjCells: function() {
+			var clist = new this.klass.CellList();
+			clist.add(this.relcell(-1, -2));
+			clist.add(this.relcell(1, -2));
+			clist.add(this.relcell(-2, 0));
+			clist.add(this.relcell(2, 0));
+			clist.add(this.relcell(-1, 2));
+			clist.add(this.relcell(1, 2));
+			return clist.filter(function(c) {
+				return !c.isnull;
+			});
+		}
 	},
 	Board: {
 		cols: 6, // ※本スクリプトでは一番上の段のマスの数を表すこととする.
@@ -541,13 +554,7 @@
 				if (!cell.isValidNum()) {
 					continue;
 				}
-				var clist = new this.klass.CellList();
-				clist.add(cell.relcell(-1, -2));
-				clist.add(cell.relcell(1, -2));
-				clist.add(cell.relcell(-2, 0));
-				clist.add(cell.relcell(2, 0));
-				clist.add(cell.relcell(-1, 2));
-				clist.add(cell.relcell(1, 2));
+				var clist = cell.adjCells();
 				if (
 					cell.qnum ===
 					clist.filter(function(cell) {
diff --git a/test/.eslintrc.json b/test/.eslintrc.json
index 32ea65e99..46d1a97dc 100644
--- a/test/.eslintrc.json
+++ b/test/.eslintrc.json
@@ -4,31 +4,32 @@
     "node": true
   },
   "parserOptions": {
-    "ecmaVersion": 6
+    "ecmaVersion": 6,
+    "sourceType": "module"
   },
   "globals": {
     "describe": "readonly",
     "it": "readonly"
   },
-  "extends": "eslint:recommended",      // Implement recommended rules
+  "extends": "eslint:recommended", // Implement recommended rules
   "rules": {
-    "curly": ["error", "all"],          // Error for no curly brancket in loop or conditions
-    "no-unused-vars":                   // Error for unused variables, not detect arguments
-        ["error", {"args": "none"}],
-    "no-undef": "error",                // Error for unused variable (that will become global variable)
-    "new-cap": "error",                 // Error for lowercase first letter or constructor call as function
-    "eqeqeq": ["error", "always"],      // Error for ==, != to compare
-    "no-use-before-define":             // Error for using variable before definition
-        ["error", {"functions":false, "classes":false}],
+    "curly": ["error", "all"], // Error for no curly brancket in loop or conditions
+    // Error for unused variables, not detect arguments
+    "no-unused-vars": ["error", { "args": "none" }],
+    "no-undef": "error", // Error for unused variable (that will become global variable)
+    "new-cap": "error", // Error for lowercase first letter or constructor call as function
+    "eqeqeq": ["error", "always"], // Error for ==, != to compare
+    // Error for using variable before definition
+    "no-use-before-define": ["error", { "functions": false, "classes": false }],
     "comma-dangle": ["error", "never"], // Error for trailing comma
-    "no-redeclare": "error",            // Error for redefine variable
+    "no-redeclare": "error", // Error for redefine variable
     //"block-scoped-var": "warn",       // Warn var declaration inside block scope
-    "no-empty": "off",                  // Allow empty block statements
-    "no-useless-escape": "off",         // Allow unnessesary escape charactors
-    "no-extra-boolean-cast": "off",     // Allow to use boolean cast for boolean value
-    "no-mixed-spaces-and-tabs": "off",  // Allow to use spaces and tabs for indent
-    "dot-notation": "off",              // Allow object access via obj["name"]
-    "no-loop-func": "off",              // Allow function definition in loop
+    "no-empty": "off", // Allow empty block statements
+    "no-useless-escape": "off", // Allow unnessesary escape charactors
+    "no-extra-boolean-cast": "off", // Allow to use boolean cast for boolean value
+    "no-mixed-spaces-and-tabs": "off", // Allow to use spaces and tabs for indent
+    "dot-notation": "off", // Allow object access via obj["name"]
+    "no-loop-func": "off", // Allow function definition in loop
     "no-console": "off"
   }
 }
diff --git a/test/load_testdata.js b/test/load_testdata.js
index 7b61fd2f8..3e7d01c8b 100644
--- a/test/load_testdata.js
+++ b/test/load_testdata.js
@@ -1,6 +1,6 @@
 // test/load_testdata.js
 
-var pzpr = require("../dist/js/pzpr.js");
+import pzpr from "../dist/js/pzpr.concat.js";
 
 // Load test data
 var testdata = {};
@@ -16,4 +16,4 @@ pzpr.variety.each(function(pid) {
 	require("./script/" + pid + ".js");
 });
 
-module.exports = testdata;
+export default testdata;
diff --git a/test/puzzle/answer_test.js b/test/puzzle/answer_test.js
index 43299f190..eb1f11f48 100644
--- a/test/puzzle/answer_test.js
+++ b/test/puzzle/answer_test.js
@@ -2,9 +2,9 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../dist/js/pzpr.js");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
-var testdata = require("../load_testdata.js");
+import testdata from "../load_testdata.js";
 
 pzpr.variety.each(function(pid) {
 	describe(pid + " answer test", function() {
diff --git a/test/puzzle/boardexec_test.js b/test/puzzle/boardexec_test.js
index 6df0a3154..50751de10 100644
--- a/test/puzzle/boardexec_test.js
+++ b/test/puzzle/boardexec_test.js
@@ -2,9 +2,9 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../dist/js/pzpr.js");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
-var testdata = require("../load_testdata.js");
+import testdata from "../load_testdata.js";
 
 function assert_equal_board(bd1, bd2) {
 	bd1.compareData(bd2, function(group, c, a) {
diff --git a/test/puzzle/config_test.js b/test/puzzle/config_test.js
index 6eb0fed52..2d47a0bb1 100644
--- a/test/puzzle/config_test.js
+++ b/test/puzzle/config_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../dist/js/pzpr.js");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 describe("Config test", function() {
 	var puzzle = new pzpr.Puzzle();
diff --git a/test/puzzle/encode_test.js b/test/puzzle/encode_test.js
index 5703eac85..be793b26c 100644
--- a/test/puzzle/encode_test.js
+++ b/test/puzzle/encode_test.js
@@ -2,9 +2,9 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../dist/js/pzpr.js");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
-var testdata = require("../load_testdata.js");
+import testdata from "../load_testdata.js";
 
 function assert_equal_board(bd1, bd2) {
 	bd1.compareData(bd2, function(group, c, a) {
diff --git a/test/puzzle/filedata_test.js b/test/puzzle/filedata_test.js
index ea8b9d919..60102e59a 100644
--- a/test/puzzle/filedata_test.js
+++ b/test/puzzle/filedata_test.js
@@ -2,9 +2,9 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../dist/js/pzpr.js");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
-var testdata = require("../load_testdata.js");
+import testdata from "../load_testdata.js";
 
 function assert_equal_board(bd1, bd2, iskanpen) {
 	var pid = bd1.pid;
diff --git a/test/puzzle/input_test.js b/test/puzzle/input_test.js
index fae9fe32e..b46068ceb 100644
--- a/test/puzzle/input_test.js
+++ b/test/puzzle/input_test.js
@@ -2,9 +2,9 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../dist/js/pzpr.js");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
-var testdata = require("../load_testdata.js");
+import testdata from "../load_testdata.js";
 
 function execmouse(puzzle, strs) {
 	var matches = (strs[1].match(/(left|right)(.*)/)[2] || "").match(/x([0-9]+)/);
diff --git a/test/puzzle/operation_test.js b/test/puzzle/operation_test.js
index 978a6b021..e1941c780 100644
--- a/test/puzzle/operation_test.js
+++ b/test/puzzle/operation_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../dist/js/pzpr.js");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 describe("Trial mode test", function() {
 	it("Enter test", function() {
diff --git a/test/puzzle/render_test.js b/test/puzzle/render_test.js
index 6693a5e36..84e56f5ee 100644
--- a/test/puzzle/render_test.js
+++ b/test/puzzle/render_test.js
@@ -2,9 +2,9 @@
 // jshint node:true, browser:false, esnext:true
 /* global describe:false, it:false */
 
-var pzpr = require("../../dist/js/pzpr.js");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
-var testdata = require("../load_testdata.js");
+import testdata from "../load_testdata.js";
 
 pzpr.variety.each(function(pid) {
 	describe(pid + " render test", function() {
diff --git a/test/pzpr/parser_test.js b/test/pzpr/parser_test.js
index 79408024c..66fd8a12f 100644
--- a/test/pzpr/parser_test.js
+++ b/test/pzpr/parser_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/aho_test.js b/test/variety/aho_test.js
index 3636fdc91..11d322d5a 100644
--- a/test/variety/aho_test.js
+++ b/test/variety/aho_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/amibo_test.js b/test/variety/amibo_test.js
index 6888c816e..6d2fbe205 100644
--- a/test/variety/amibo_test.js
+++ b/test/variety/amibo_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/ayeheya_test.js b/test/variety/ayeheya_test.js
index 54fe51330..bf2af8bfb 100644
--- a/test/variety/ayeheya_test.js
+++ b/test/variety/ayeheya_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/cbblock_test.js b/test/variety/cbblock_test.js
index 7f03b05bc..ffd3730c6 100644
--- a/test/variety/cbblock_test.js
+++ b/test/variety/cbblock_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/curvedata_test.js b/test/variety/curvedata_test.js
index cf809d7b4..c4618be48 100644
--- a/test/variety/curvedata_test.js
+++ b/test/variety/curvedata_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/fivecells_test.js b/test/variety/fivecells_test.js
index 4e03c2fa6..dd43cd8eb 100644
--- a/test/variety/fivecells_test.js
+++ b/test/variety/fivecells_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/gokigen_test.js b/test/variety/gokigen_test.js
index e1adc1142..561dde250 100644
--- a/test/variety/gokigen_test.js
+++ b/test/variety/gokigen_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/herugolf_test.js b/test/variety/herugolf_test.js
index fca2b5069..dc4941cfe 100644
--- a/test/variety/herugolf_test.js
+++ b/test/variety/herugolf_test.js
@@ -1,6 +1,6 @@
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/lits_test.js b/test/variety/lits_test.js
index 107df18b6..5a46b2b1e 100644
--- a/test/variety/lits_test.js
+++ b/test/variety/lits_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/onsen_test.js b/test/variety/onsen_test.js
index b063da972..9846698b8 100644
--- a/test/variety/onsen_test.js
+++ b/test/variety/onsen_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/pipelink_test.js b/test/variety/pipelink_test.js
index 5b04aff5c..6bdf82726 100644
--- a/test/variety/pipelink_test.js
+++ b/test/variety/pipelink_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/ringring_test.js b/test/variety/ringring_test.js
index d0654a994..0a9b7fde8 100644
--- a/test/variety/ringring_test.js
+++ b/test/variety/ringring_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/slalom_test.js b/test/variety/slalom_test.js
index 61fe8e00b..4369c7599 100644
--- a/test/variety/slalom_test.js
+++ b/test/variety/slalom_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/tapa_test.js b/test/variety/tapa_test.js
index d61340272..985df46e2 100644
--- a/test/variety/tapa_test.js
+++ b/test/variety/tapa_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/tentaisho_test.js b/test/variety/tentaisho_test.js
index 46550fde5..a542518f3 100644
--- a/test/variety/tentaisho_test.js
+++ b/test/variety/tentaisho_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();
 
diff --git a/test/variety/yajilin_test.js b/test/variety/yajilin_test.js
index 765e93ead..351fde1f7 100644
--- a/test/variety/yajilin_test.js
+++ b/test/variety/yajilin_test.js
@@ -2,7 +2,7 @@
 
 var assert = require("assert");
 
-var pzpr = require("../../");
+import pzpr from "../../dist/js/pzpr.concat.js";
 
 var puzzle = new pzpr.Puzzle();