```ruby
require 'thor'

module RomajiKit
  class CLI < Thor
    desc 'hepburnize', 'Convert kana to hepburn'
    option :upcase, type: :boolean, aliases: '-u'
    def hepburnize(text)
      puts Converter.hepburnize(text, options[:upcase])
    end
  end

  CLI.start
end
```

Add `nihon` method for CLI
user
```ruby
require 'thor'

module RomajiKit
  class CLI < Thor
    class_option :upcase, type: :boolean, aliases: '-u'

    desc 'hepburnize', 'Convert kana to hepburn'
    def hepburnize(text)
      puts Converter.hepburnize(text, options[:upcase])
    end

    desc 'nihon', 'Convert kana to Nihon-shiki romaji'
    def nihon(text)
      puts Converter.nihon(text, options[:upcase])
    end
  end

  CLI.start
end
```
assistant