diff --git a/Gemfile b/Gemfile
index 1c8e0d8..78384f9 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,13 +4,16 @@ source 'https://rubygems.org'
 
 # gemspec
 gem 'bundler'
-#gem 'ruby-debug-ide'
 gem 'pry'
-#gem 'pycall'
 gem 'rake'
-# gem 'rspec'
 gem 'minitest'
 gem 'simplecov'
+gem 'bmi'
+
+# dependent library
+#gem 'ruby-debug-ide'
+#gem 'pycall'
+#gem 'rspec'
 #gem 'solargraph'
 #gem 'nokogiri'
 #gem 'httparty'
diff --git a/coverage/.resultset.json b/coverage/.resultset.json
index 7221588..b6cb2c2 100644
--- a/coverage/.resultset.json
+++ b/coverage/.resultset.json
@@ -502,7 +502,7 @@
         ]
       }
     },
-    "timestamp": 1713261018
+    "timestamp": 1715145617
   },
   "RSpec": {
     "coverage": {
diff --git a/katakana_runner.rb b/katakana_runner.rb
index 963cbee..3e135d4 100644
--- a/katakana_runner.rb
+++ b/katakana_runner.rb
@@ -4,11 +4,6 @@
 
 # Katakana Runner
 class KatakanaRunner
-  # default encoding utf-8, change encode here.
-  def self.encoding_style
-    Encoding.default_internal = 'UTF-8'
-    Encoding.default_external = 'UTF-8'
-  end
 
   def self.run1
     encoding_style
diff --git a/mini_test_runner.rb b/mini_test_runner.rb
index 46f8fbe..f4dab9e 100644
--- a/mini_test_runner.rb
+++ b/mini_test_runner.rb
@@ -6,12 +6,6 @@
 class MiniTestFile
   attr_reader :mini_test, :mini_unit
 
-  # Default encoding utf8, Encoding change here.
-  def encoding_style
-    Encoding.default_internal = 'UTF-8'
-    Encoding.default_external = 'UTF-8'
-  end
-
   def initialize
     encoding_style
     @mini_test = Mini(true, '/GitHub/zinbeijett/mini_test')
diff --git a/req/katakana.rb b/req/katakana.rb
index 21e3fec..d5efb3e 100644
--- a/req/katakana.rb
+++ b/req/katakana.rb
@@ -4,5 +4,6 @@
 
 require 'open3'
 require 'tanraku'
+require 'bmi'
 
 # --------------------------------------
diff --git a/req/minitest.rb b/req/minitest.rb
index 024831f..76b5897 100644
--- a/req/minitest.rb
+++ b/req/minitest.rb
@@ -7,4 +7,5 @@
 require 'minitest/unit'
 require 'minitest/runner'
 require 'tanraku'
+require 'bmi'
 # --------------------------------------
diff --git a/req/romaji.rb b/req/romaji.rb
index 21e3fec..d5efb3e 100644
--- a/req/romaji.rb
+++ b/req/romaji.rb
@@ -4,5 +4,6 @@
 
 require 'open3'
 require 'tanraku'
+require 'bmi'
 
 # --------------------------------------
diff --git a/romaji_runner.rb b/romaji_runner.rb
index d99b454..dd3596b 100644
--- a/romaji_runner.rb
+++ b/romaji_runner.rb
@@ -4,77 +4,72 @@
 
 # Romaji Runner
 class RomajiRunner
-  # default encoding utf-8, change encode here.
-  def self.encodig_style
-    Encoding.default_internal = 'UTF-8'
-    Encoding.default_external = 'UTF-8'
-  end
 
   def self.run1
-    encodig_style
+    encoding_style
     stdout_rb, _stderr_rb, _status_rb = Open3.capture3("ruby #{File.dirname(__FILE__)}/shell/romaji_runner_1.rb")
 
     puts stdout_rb
   end
 
   def self.run2
-    encodig_style
+    encoding_style
     stdout_rb, _stderr_rb, _status_rb = Open3.capture3("ruby #{File.dirname(__FILE__)}/shell/romaji_runner_2.rb")
 
     puts stdout_rb
   end
 
   def self.run3
-    encodig_style
+    encoding_style
     stdout_rb, _stderr_rb, _status_rb = Open3.capture3("ruby #{File.dirname(__FILE__)}/shell/romaji_runner_3.rb")
 
     puts stdout_rb
   end
 
   def self.run4
-    encodig_style
+    encoding_style
     stdout_rb, _stderr_rb, _status_rb = Open3.capture3("ruby #{File.dirname(__FILE__)}/shell/romaji_runner_4.rb")
 
     puts stdout_rb
   end
 
   def self.run5
-    encodig_style
+    encoding_style
     stdout_rb, _stderr_rb, _status_rb = Open3.capture3("ruby #{File.dirname(__FILE__)}/shell/romaji_runner_5.rb")
 
     puts stdout_rb
   end
 
   def self.run6
-    encodig_style
+    encoding_style
     stdout_rb, _stderr_rb, _status_rb = Open3.capture3("ruby #{File.dirname(__FILE__)}/shell/romaji_runner_6.rb")
 
     puts stdout_rb
   end
 
   def self.run7
-    encodig_style
+    encoding_style
     stdout_rb, _stderr_rb, _status_rb = Open3.capture3("ruby #{File.dirname(__FILE__)}/shell/romaji_runner_7.rb")
 
     puts stdout_rb
   end
 
   def self.run8
-    encodig_style
+    encoding_style
     stdout_rb, _stderr_rb, _status_rb = Open3.capture3("ruby #{File.dirname(__FILE__)}/shell/romaji_runner_8.rb")
 
     puts stdout_rb
   end
 
   def self.run9
-    encodig_style
+    encoding_style
     stdout_rb, _stderr_rb, _status_rb = Open3.capture3("ruby #{File.dirname(__FILE__)}/shell/romaji_runner_9.rb")
 
     puts stdout_rb
   end
 
   def self.run10
-    encodig_style
+    encoding_style
     stdout_rb, _stderr_rb, _status_rb = Open3.capture3("ruby #{File.dirname(__FILE__)}/shell/romaji_runner_10.rb")
 
     puts stdout_rb
@@ -101,7 +96,7 @@ def self.run10
   threads.each { |thr| thr.join.value }
 rescue StandardError => e
   puts e.backtrace
-  encodig_style.tanraku_exit
+  encoding_style.tanraku_exit
 rescue Interrupt
   # [result] false ↔ [default] true
   # puts Thread.current.report_on_exception