Internal characters are displayed in 'showcmd' area

[domekomi]

My config is as follows:

set nocompatible
set noshowmode
set noshowcmd
set encoding=utf-8
let g:submode_keep_leaving_key=1
call submode#enter_with('cmd', 'n', '', '<Space>j', ':echo "j"<CR>')

When I press <Space>j<Space>j<Space>j<Space>j<Space>j repeatedly, ÂÂÂÂÂ and @=@=@=@=@= are displayed alternately in 'showcmd' area.

These characters are not displayed when showmode or showcmd is enabled.