全角の日本語のかな文字を半角にするRubyスクリプト

s="ゔぉー…"

argv = ARGV[0]
# s = argv
s = argv.gsub(//,'')

s.gsub!(/あ/,"ｱ")
s.gsub!(/い/,"ｲ")
s.gsub!(/う/,"ｳ")
s.gsub!(/え/,"ｴ")
s.gsub!(/お/,"ｵ")
s.gsub!(/か/,"ｶ")
s.gsub!(/き/,"ｷ")
s.gsub!(/く/,"ｸ")
s.gsub!(/け/,"ｹ")
s.gsub!(/こ/,"ｺ")
s.gsub!(/さ/,"ｻ")
s.gsub!(/し/,"ｼ")
s.gsub!(/す/,"ｽ")
s.gsub!(/せ/,"ｾ")
s.gsub!(/そ/,"ｿ")
s.gsub!(/た/,"ﾀ")
s.gsub!(/ち/,"ﾁ")
s.gsub!(/つ/,"ﾂ")
s.gsub!(/て/,"ﾃ")
s.gsub!(/と/,"ﾄ")
s.gsub!(/な/,"ﾅ")
s.gsub!(/に/,"ﾆ")
s.gsub!(/ぬ/,"ﾇ")
s.gsub!(/ね/,"ﾈ")
s.gsub!(/の/,"ﾉ")
s.gsub!(/は/,"ﾊ")
s.gsub!(/ひ/,"ﾋ")
s.gsub!(/ふ/,"ﾌ")
s.gsub!(/へ/,"ﾍ")
s.gsub!(/ほ/,"ﾎ")
s.gsub!(/ま/,"ﾏ")
s.gsub!(/み/,"ﾐ")
s.gsub!(/む/,"ﾑ")
s.gsub!(/め/,"ﾒ")
s.gsub!(/も/,"ﾓ")
s.gsub!(/や/,"ﾔ")
s.gsub!(/ゆ/,"ﾕ")
s.gsub!(/よ/,"ﾖ")
s.gsub!(/ら/,"ﾗ")
s.gsub!(/り/,"ﾘ")
s.gsub!(/る/,"ﾙ")
s.gsub!(/れ/,"ﾚ")
s.gsub!(/ろ/,"ﾛ")
s.gsub!(/わ/,"ﾜ")
s.gsub!(/を/,"ｦ")
s.gsub!(/ん/,"ﾝ")
s.gsub!(/ゔ/,"ｳﾞ")
s.gsub!(/が/,"ｶﾞ")
s.gsub!(/ぎ/,"ｷﾞ")
s.gsub!(/ぐ/,"ｸﾞ")
s.gsub!(/げ/,"ｹﾞ")
s.gsub!(/ご/,"ｺﾞ")
s.gsub!(/ざ/,"ｻﾞ")
s.gsub!(/じ/,"ｼﾞ")
s.gsub!(/ず/,"ｽﾞ")
s.gsub!(/ぜ/,"ｾﾞ")
s.gsub!(/ぞ/,"ｿﾞ")
s.gsub!(/だ/,"ﾀﾞ")
s.gsub!(/ぢ/,"ﾁﾞ")
s.gsub!(/づ/,"ﾂﾞ")
s.gsub!(/で/,"ﾃﾞ")
s.gsub!(/ど/,"ﾄﾞ")
s.gsub!(/ば/,"ﾊﾞ")
s.gsub!(/び/,"ﾋﾞ")
s.gsub!(/ぶ/,"ﾌﾞ")
s.gsub!(/べ/,"ﾍﾞ")
s.gsub!(/ぼ/,"ﾎﾞ")
s.gsub!(/ぱ/,"ﾊﾟ")
s.gsub!(/ぴ/,"ﾋﾟ")
s.gsub!(/ぷ/,"ﾌﾟ")
s.gsub!(/ぺ/,"ﾍﾟ")
s.gsub!(/ぽ/,"ﾎﾟ")
s.gsub!(/ぁ/,"ｧ")
s.gsub!(/ぃ/,"ｨ")
s.gsub!(/ぅ/,"ｩ")
s.gsub!(/ぇ/,"ｪ")
s.gsub!(/ぉ/,"ｫ")
s.gsub!(/ゃ/,"ｬ")
s.gsub!(/ゅ/,"ｭ")
s.gsub!(/ょ/,"ｮ")
s.gsub!(/っ/,"ｯ")
s.gsub!(/ア/,"ｱ")
s.gsub!(/イ/,"ｲ")
s.gsub!(/ウ/,"ｳ")
s.gsub!(/エ/,"ｴ")
s.gsub!(/オ/,"ｵ")
s.gsub!(/カ/,"ｶ")
s.gsub!(/キ/,"ｷ")
s.gsub!(/ク/,"ｸ")
s.gsub!(/ケ/,"ｹ")
s.gsub!(/コ/,"ｺ")
s.gsub!(/サ/,"ｻ")
s.gsub!(/シ/,"ｼ")
s.gsub!(/ス/,"ｽ")
s.gsub!(/セ/,"ｾ")
s.gsub!(/ソ/,"ｿ")
s.gsub!(/タ/,"ﾀ")
s.gsub!(/チ/,"ﾁ")
s.gsub!(/ツ/,"ﾂ")
s.gsub!(/テ/,"ﾃ")
s.gsub!(/ト/,"ﾄ")
s.gsub!(/ナ/,"ﾅ")
s.gsub!(/ニ/,"ﾆ")
s.gsub!(/ヌ/,"ﾇ")
s.gsub!(/ネ/,"ﾈ")
s.gsub!(/ノ/,"ﾉ")
s.gsub!(/ハ/,"ﾊ")
s.gsub!(/ヒ/,"ﾋ")
s.gsub!(/フ/,"ﾌ")
s.gsub!(/ヘ/,"ﾍ")
s.gsub!(/ホ/,"ﾎ")
s.gsub!(/マ/,"ﾏ")
s.gsub!(/ミ/,"ﾐ")
s.gsub!(/ム/,"ﾑ")
s.gsub!(/メ/,"ﾒ")
s.gsub!(/モ/,"ﾓ")
s.gsub!(/ヤ/,"ﾔ")
s.gsub!(/ユ/,"ﾕ")
s.gsub!(/ヨ/,"ﾖ")
s.gsub!(/ラ/,"ﾗ")
s.gsub!(/リ/,"ﾘ")
s.gsub!(/ル/,"ﾙ")
s.gsub!(/レ/,"ﾚ")
s.gsub!(/ロ/,"ﾛ")
s.gsub!(/ワ/,"ﾜ")
s.gsub!(/ヲ/,"ｦ")
s.gsub!(/ン/,"ﾝ")
s.gsub!(/ヴ/,"ｳﾞ")
s.gsub!(/ガ/,"ｶﾞ")
s.gsub!(/ギ/,"ｷﾞ")
s.gsub!(/グ/,"ｸﾞ")
s.gsub!(/ゲ/,"ｹﾞ")
s.gsub!(/ゴ/,"ｺﾞ")
s.gsub!(/ザ/,"ｻﾞ")
s.gsub!(/ジ/,"ｼﾞ")
s.gsub!(/ズ/,"ｽﾞ")
s.gsub!(/ゼ/,"ｾﾞ")
s.gsub!(/ゾ/,"ｿﾞ")
s.gsub!(/ダ/,"ﾀﾞ")
s.gsub!(/ヂ/,"ﾁﾞ")
s.gsub!(/ヅ/,"ﾂﾞ")
s.gsub!(/デ/,"ﾃﾞ")
s.gsub!(/ド/,"ﾄﾞ")
s.gsub!(/バ/,"ﾊﾞ")
s.gsub!(/ビ/,"ﾋﾞ")
s.gsub!(/ブ/,"ﾌﾞ")
s.gsub!(/ベ/,"ﾍﾞ")
s.gsub!(/ボ/,"ﾎﾞ")
s.gsub!(/パ/,"ﾊﾟ")
s.gsub!(/ピ/,"ﾋﾟ")
s.gsub!(/プ/,"ﾌﾟ")
s.gsub!(/ペ/,"ﾍﾟ")
s.gsub!(/ポ/,"ﾎﾟ")
s.gsub!(/ァ/,"ｧ")
s.gsub!(/ィ/,"ｨ")
s.gsub!(/ゥ/,"ｩ")
s.gsub!(/ェ/,"ｪ")
s.gsub!(/ォ/,"ｫ")
s.gsub!(/ャ/,"ｬ")
s.gsub!(/ュ/,"ｭ")
s.gsub!(/ョ/,"ｮ")
s.gsub!(/ッ/,"ｯ")

puts s

$ ruby かな文字半角変換.rb ゔぉー…
ｳﾞｫー…