N11n::$decomposable does not include Hiragana characters

[himorin]

N11n::$decomposable map lists decomposable code points with NFC as key and NFD as value.
Japanese Katakana characters are listed, but could not find Hiragana characters.

Or, script could be updated with newly introduced (PHP 5.3) Normalizer class?
https://www.php.net/manual/en/class.normalizer.php