diff --git a/challengeA/shogo_takasaki/data/plans.json b/challengeA/shogo_takasaki/data/plans.json
new file mode 100644
index 000000000..ed803aeb8
--- /dev/null
+++ b/challengeA/shogo_takasaki/data/plans.json
@@ -0,0 +1,69 @@
+{
+  "suppliers": [
+    {
+      "provider_name": "東京電力エナジーパートナー",
+      "plan_name": "従量電灯B",
+      "basic_price": {
+        "10": 286.00,
+        "15": 429.00,
+        "20": 572.00,
+        "30": 858.00,
+        "40": 1144.00,
+        "50": 1430.00,
+        "60": 1716.00
+      },
+      "usage_price": {
+        "0": 19.88,
+        "301": 30.57,
+        "121": 26.48
+      }
+    },
+    {
+      "provider_name": "Looopでんき",
+      "plan_name": "おうちプラン",
+      "basic_price": {
+        "10": 0.00,
+        "15": 0.00,
+        "20": 0.00,
+        "30": 0.00,
+        "40": 0.00,
+        "50": 0.00,
+        "60": 0.00
+      },
+      "usage_price": {
+        "0": 26.40
+      }
+    },
+    {
+      "provider_name": "東京ガス",
+      "plan_name": "ずっとも電気１",
+      "basic_price": {
+        "30": 858.00,
+        "40": 1144.00,
+        "50": 1430.00,
+        "60": 1716.00
+      },
+      "usage_price": {
+        "0": 23.67,
+        "141": 23.88,
+        "351": 26.41
+      }
+    },
+    {
+      "provider_name": "JXTGでんき",
+      "plan_name": "従量電灯B たっぷりプラン",
+      "basic_price": {
+        "30": 858.00,
+        "40": 1144.00,
+        "50": 1430.00,
+        "60": 1716.80
+      },
+      "usage_price": {
+        "0": 19.88,
+        "121": 26.48,
+        "301": 25.08,
+        "601": 26.15
+      }
+    }
+  ]
+}
diff --git a/challengeA/shogo_takasaki/src/plan.rb b/challengeA/shogo_takasaki/src/plan.rb
new file mode 100644
index 000000000..9e3cd9b3e
--- /dev/null
+++ b/challengeA/shogo_takasaki/src/plan.rb
@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+# display plan info
+class Plan
+  attr_reader :provider_name, :plan_name, :basic_price_list, :usage_price_list
+
+  module Message
+    NO_BASIC_PRICE = '基本料金設定無し'
+    NO_UNIT_PRICE = '従量料金設定無し'
+  end
+
+  def initialize(plan)
+    @provider_name = plan['provider_name']
+    @plan_name = plan['plan_name']
+    @basic_price_list = plan['basic_price']
+    @usage_price_list = plan['usage_price']
+  end
+
+  def basic_price(ampere, usage)
+    raise Message::NO_BASIC_PRICE if @basic_price_list[ampere.to_s].nil?
+    return @basic_price_list[ampere.to_s] / 2 if usage.zero?
+
+    @basic_price_list[ampere.to_s]
+  end
+
+  def unit_price(usage)
+    result = @usage_price_list.select { |k, v| k.to_i <= usage }.max.last
+    return result unless result.nil?
+
+    raise Message::NO_UNIT_PRICE
+  end
+
+  def usage_price(usage)
+    unit_price(usage) * usage
+  end
+
+  def price(ampere, usage)
+    basic_price(ampere, usage) + usage_price(usage)
+  end
+
+  def price_with_tax(ampere, usage)
+    (price(ampere, usage) + (price(ampere, usage) * Simulator::TAX_RATE)).to_i
+  end
+
+  def display(ampere, usage)
+    {
+      provider_name: provider_name,
+      plan_name: plan_name,
+      price: price_with_tax(ampere, usage)
+    }
+  end
+end
diff --git a/challengeA/shogo_takasaki/src/simulator.rb b/challengeA/shogo_takasaki/src/simulator.rb
new file mode 100644
index 000000000..b6ca0a437
--- /dev/null
+++ b/challengeA/shogo_takasaki/src/simulator.rb
@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+require 'json'
+
+# Simulator for electric usage
+class Simulator
+  attr_reader :ampere, :usage, :plans
+
+  TAX_RATE = 0.1
+
+  def initialize(ampere, usage)
+    @ampere = ampere
+    @usage = usage
+    File.open('../data/plans.json') do |f|
+      @plans = JSON.load(f)
+    end
+  end
+
+  def simulate
+    @plans['suppliers'].map do |plan|
+      Plan.new(plan).display(@ampere, @usage)
+    end
+  end
+end
diff --git a/challengeA/shogo_takasaki/test/plan_test.rb b/challengeA/shogo_takasaki/test/plan_test.rb
new file mode 100644
index 000000000..78eba62fb
--- /dev/null
+++ b/challengeA/shogo_takasaki/test/plan_test.rb
@@ -0,0 +1,176 @@
+# frozen_string_literal: true
+
+require 'minitest/autorun'
+require '../src/plan'
+require '../src/simulator'
+require 'json'
+
+# display plan info test
+class PlanTest < Minitest::Test
+  def setup
+    File.open("../data/plans.json") do |f|
+      @plans = JSON.load(f)
+    end
+    @tokyo_energy = Plan.new(@plans['suppliers'][0])
+    @looop = Plan.new(@plans['suppliers'][1])
+    @tokyo_gas = Plan.new(@plans['suppliers'][2])
+    @jxtg = Plan.new(@plans['suppliers'][3])
+  end
+
+  def test_tokyo_energy_basic_price
+    assert_equal 143, @tokyo_energy.basic_price(10, 0)
+    assert_equal 286, @tokyo_energy.basic_price(10, 100)
+    assert_equal 429, @tokyo_energy.basic_price(15, 100)
+    assert_equal 572, @tokyo_energy.basic_price(20, 100)
+    assert_equal 858, @tokyo_energy.basic_price(30, 100)
+    assert_equal 1144, @tokyo_energy.basic_price(40, 100)
+    assert_equal 1430, @tokyo_energy.basic_price(50, 100)
+    assert_equal 1716, @tokyo_energy.basic_price(60, 100)
+    e = assert_raises RuntimeError do @tokyo_energy.basic_price(61, 100) end
+    assert_equal Plan::Message::NO_BASIC_PRICE, e.message
+    e = assert_raises RuntimeError do @tokyo_energy.basic_price(61, 0) end
+    assert_equal Plan::Message::NO_BASIC_PRICE, e.message
+  end
+
+  def test_loops_basic_price
+    assert_equal 0, @looop.basic_price(10, 100)
+    assert_equal 0, @looop.basic_price(20, 100)
+    assert_equal 0, @looop.basic_price(30, 100)
+    assert_equal 0, @looop.basic_price(40, 100)
+    assert_equal 0, @looop.basic_price(50, 100)
+    assert_equal 0, @looop.basic_price(60, 100)
+    e = assert_raises RuntimeError do @looop.basic_price(61, 100) end
+    assert_equal Plan::Message::NO_BASIC_PRICE, e.message
+  end
+
+  def test_tokyo_gas_basic_price
+    assert_equal 429, @tokyo_gas.basic_price(30, 0)
+    assert_equal 858, @tokyo_gas.basic_price(30, 100)
+    assert_equal 1144, @tokyo_gas.basic_price(40, 100)
+    assert_equal 1430, @tokyo_gas.basic_price(50, 100)
+    assert_equal 1716, @tokyo_gas.basic_price(60, 100)
+    e = assert_raises RuntimeError do @tokyo_gas.basic_price(20, 100) end
+    assert_equal Plan::Message::NO_BASIC_PRICE, e.message
+  end
+
+  def test_jxtg_basic_price
+    assert_equal 429, @jxtg.basic_price(30, 0)
+    assert_equal 858, @jxtg.basic_price(30, 100)
+    assert_equal 1144, @jxtg.basic_price(40, 100)
+    assert_equal 1430, @jxtg.basic_price(50, 100)
+    assert_equal 1716.80, @jxtg.basic_price(60, 100)
+    e = assert_raises RuntimeError do @jxtg.basic_price(20, 100) end
+    assert_equal Plan::Message::NO_BASIC_PRICE, e.message
+  end
+
+  def test_tokyo_energy_unit_price
+    assert_equal 19.88, @tokyo_energy.unit_price(0)
+    assert_equal 19.88, @tokyo_energy.unit_price(119)
+    assert_equal 19.88, @tokyo_energy.unit_price(120)
+    assert_equal 26.48, @tokyo_energy.unit_price(121)
+    assert_equal 26.48, @tokyo_energy.unit_price(300)
+    assert_equal 30.57, @tokyo_energy.unit_price(301)
+    assert_equal 30.57, @tokyo_energy.unit_price(400)
+  end
+
+  def test_loops_unit_price
+    assert_equal 26.40, @looop.unit_price(0)
+    assert_equal 26.40, @looop.unit_price(119)
+    assert_equal 26.40, @looop.unit_price(120)
+    assert_equal 26.40, @looop.unit_price(121)
+    assert_equal 26.40, @looop.unit_price(300)
+    assert_equal 26.40, @looop.unit_price(301)
+    assert_equal 26.40, @looop.unit_price(400)
+  end
+
+  def test_tokyo_gas_unit_price
+    assert_equal 23.67, @tokyo_gas.unit_price(0)
+    assert_equal 23.67, @tokyo_gas.unit_price(139)
+    assert_equal 23.67, @tokyo_gas.unit_price(140)
+    assert_equal 23.88, @tokyo_gas.unit_price(141)
+    assert_equal 23.88, @tokyo_gas.unit_price(349)
+    assert_equal 23.88, @tokyo_gas.unit_price(350)
+    assert_equal 26.41, @tokyo_gas.unit_price(351)
+  end
+
+  def test_jxtg_unit_price
+    assert_equal 19.88, @jxtg.unit_price(0)
+    assert_equal 19.88, @jxtg.unit_price(120)
+    assert_equal 26.48, @jxtg.unit_price(121)
+    assert_equal 26.48, @jxtg.unit_price(300)
+    assert_equal 25.08, @jxtg.unit_price(301)
+    assert_equal 25.08, @jxtg.unit_price(600)
+    assert_equal 26.15, @jxtg.unit_price(601)
+  end
+
+  def test_additional_price
+    assert_equal @tokyo_energy.unit_price(0) * 0, @tokyo_energy.usage_price(0)
+    assert_equal @tokyo_energy.unit_price(119) * 119, @tokyo_energy.usage_price(119)
+    assert_equal @tokyo_energy.unit_price(120) * 120, @tokyo_energy.usage_price(120)
+    assert_equal @tokyo_energy.unit_price(121) * 121, @tokyo_energy.usage_price(121)
+    assert_equal @tokyo_energy.unit_price(300) * 300, @tokyo_energy.usage_price(300)
+    assert_equal @tokyo_energy.unit_price(301) * 301, @tokyo_energy.usage_price(301)
+    assert_equal @tokyo_energy.unit_price(400) * 400, @tokyo_energy.usage_price(400)
+
+    assert_equal @jxtg.unit_price(0) * 0, @jxtg.usage_price(0)
+    assert_equal @jxtg.unit_price(120) * 120, @jxtg.usage_price(120)
+    assert_equal @jxtg.unit_price(121) * 121, @jxtg.usage_price(121)
+    assert_equal @jxtg.unit_price(300) * 300, @jxtg.usage_price(300)
+    assert_equal @jxtg.unit_price(301) * 301, @jxtg.usage_price(301)
+    assert_equal @jxtg.unit_price(600) * 600, @jxtg.usage_price(600)
+    assert_equal @jxtg.unit_price(601) * 601, @jxtg.usage_price(601)
+  end
+
+  def test_price
+    assert_equal @tokyo_energy.basic_price(10, 0) + @tokyo_energy.usage_price(0), @tokyo_energy.price(10, 0)
+    assert_equal @tokyo_energy.basic_price(15, 119) + @tokyo_energy.usage_price(119), @tokyo_energy.price(15, 119)
+    assert_equal @tokyo_energy.basic_price(20, 120) + @tokyo_energy.usage_price(120), @tokyo_energy.price(20, 120)
+    assert_equal @tokyo_energy.basic_price(30, 121) + @tokyo_energy.usage_price(121), @tokyo_energy.price(30, 121)
+    assert_equal @tokyo_energy.basic_price(40, 300) + @tokyo_energy.usage_price(300), @tokyo_energy.price(40, 300)
+    assert_equal @tokyo_energy.basic_price(50, 301) + @tokyo_energy.usage_price(301), @tokyo_energy.price(50, 301)
+    assert_equal @tokyo_energy.basic_price(60, 400) + @tokyo_energy.usage_price(400), @tokyo_energy.price(60, 400)
+
+    assert_equal @jxtg.basic_price(30, 0) + @jxtg.usage_price(0), @jxtg.price(30, 0)
+    assert_equal @jxtg.basic_price(30, 120) + @jxtg.usage_price(120), @jxtg.price(30, 120)
+    assert_equal @jxtg.basic_price(40, 121) + @jxtg.usage_price(121), @jxtg.price(40, 121)
+    assert_equal @jxtg.basic_price(40, 300) + @jxtg.usage_price(300), @jxtg.price(40, 300)
+    assert_equal @jxtg.basic_price(50, 301) + @jxtg.usage_price(301), @jxtg.price(50, 301)
+    assert_equal @jxtg.basic_price(60, 600) + @jxtg.usage_price(600), @jxtg.price(60, 600)
+    assert_equal @jxtg.basic_price(60, 601) + @jxtg.usage_price(601), @jxtg.price(60, 601)
+  end
+
+  def test_price_with_tax
+    assert_equal (@tokyo_energy.price(60, 400) + (@tokyo_energy.price(60, 400) * Simulator::TAX_RATE)).to_i, @tokyo_energy.price_with_tax(60, 400)
+    assert_equal (@jxtg.price(30, 0) + (@jxtg.price(30, 0) * Simulator::TAX_RATE)).to_i, @jxtg.price_with_tax(30, 0)
+  end
+
+  def test_display
+    result_tokyo_energy = {
+      provider_name: '東京電力エナジーパートナー',
+      plan_name: '従量電灯B',
+      price: @tokyo_energy.price_with_tax(60, 400)
+    }
+    assert_equal result_tokyo_energy, @tokyo_energy.display(60, 400)
+
+    result_looops = {
+      provider_name: 'Looopでんき',
+      plan_name: 'おうちプラン',
+      price: @looop.price_with_tax(60, 400)
+    }
+    assert_equal result_looops, @looop.display(60, 400)
+
+    result_tokyo_gas = {
+      provider_name: '東京ガス',
+      plan_name: 'ずっとも電気１',
+      price: @tokyo_gas.price_with_tax(60, 400)
+    }
+    assert_equal result_tokyo_gas, @tokyo_gas.display(60, 400)
+
+    result_jxtg = {
+      provider_name: 'JXTGでんき',
+      plan_name: '従量電灯B たっぷりプラン',
+      price: @jxtg.price_with_tax(60, 400)
+    }
+    assert_equal result_jxtg, @jxtg.display(60, 400)
+  end
+end
diff --git a/challengeA/shogo_takasaki/test/simulator_test.rb b/challengeA/shogo_takasaki/test/simulator_test.rb
new file mode 100644
index 000000000..453537bd8
--- /dev/null
+++ b/challengeA/shogo_takasaki/test/simulator_test.rb
@@ -0,0 +1,40 @@
+# frozen_string_literal: true
+
+require 'minitest/autorun'
+require '../src/plan'
+require '../src/simulator'
+require 'json'
+
+# Simulator for electric usage test
+class SimulatorTest < Minitest::Test
+
+  def setup
+    @simulator = Simulator.new(60, 400)
+  end
+
+  def test_simulate
+    result = [
+      {
+        provider_name: "東京電力エナジーパートナー",
+        plan_name: "従量電灯B",
+        price: 15338
+      },
+      {
+        provider_name: "Looopでんき",
+        plan_name: "おうちプラン", price: 11616
+      },
+      {
+        provider_name: "東京ガス",
+        plan_name: "ずっとも電気１",
+        price: 13508
+      },
+      {
+        provider_name: "JXTGでんき",
+        plan_name: "従量電灯B たっぷりプラン",
+        price: 12923
+      }
+    ]
+    assert_equal result, @simulator.simulate
+  end
+
+end