Interesting choice to romanize Japanese. Now you have to figure out which romanization system to use (I was surprised を was romanized as o and not wo). But I do get it, I guess, because you have to wonder it would only use Hiragana or mix Kanji in:
大文字と小文字を無視する
だいもんじとこもじをむしする
Well, for the sake of being international, we should just use Katakana everywhere. That's the sanest suggestion (who's with me?):
ダイモンジトコモジヲムシスル
Of course, you're kind of screwed on a TTY, since they don't generally render unicode...so let's go back to figuring out which romanization system to use.
It doesn't really mean anything on its own. It's romanized as "Shi". If you know your Japanese, you'll know "Shi" is how you pronounce 死; or "Death". The word is not usually written in Katakana, though. There's also ツ, which is romanized as "Tsu".