Category:Japanese words with nonphonetic spellings
In modern Japanese orthography (現代仮名遣い), Japanese hiragana and katakana are used very phonetically, with exceptions that are few but notable:
The three basic particles は, へ, and を are pronounced wa, e, and o respectively, which would be normally written わ, え, and お.
Elsewhere, は is ha, and へ is he.
The spellings of は, へ, and を are from earlier stages of the language.
いう (iu, “to say”) is prescriptively ゆう (yuu).
In on'yomi and most native words, おう is pronounced as a long vowel ō, identical to おお.
In on'yomi, えい, is pronounced as a long vowel ē, identical to ええ.
Kanji are of course non-phonetic and non-notable.