@mario It's not uncommon to write it in kanji, but they're just ateji chosen to match the meaning. The etymology is quite interesting, from kawahayushi ("shameful") shifting in meaning to "pitiable" to "deserving compassion" to "loveable".
https://en.m.wiktionary.org/wiki/%E5%8F%AF%E6%84%9B%E3%81%84