What does イ stand for? 

イ

I (い in hiragana or イ in katakana) is one of the Japanese kana each of which represents one mora. い is based on the sōsho style of the kanji character 以, and イ is from the radical (left part) of the kanji character 伊. In the modern Japanese system of sound order, it occupies the second position of the syllable chart, between あ and う. Additionally, it is the first letter in Iroha, before ろ. Both represent the sound [i]. In the Ainu language, katakana イ is written as y in their Latin-based syllable chart, and a small ィ after another katakana represents a diphthong.

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