Hira2Kata was created to help you learn katakana characters in terms of the corresponding hiragana. The reference table is handy for figuring out what hiragana character(s) you need to type to get the katakana suggestion on the iPhone 12-key hiragana keyboard. The SRS page is a simplified version of the standard spaced repetition algorithm called SM-2. Your progress will be stored in the browser's local history.

The reference table and SRS both omit the extended set of katakana, which have no hiragana counterparts. These characters are use infrequently and probably best typed using romanji.

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