difficult / hard, probably impossible

difficult to apply 訓読 (kundoku)

(linguistics) kun'yomi: a reading of a kanji that is not derived from the kanji's original pronunciation borrowed from Chinese

to use the kun'yomi of a word, to read a kanji using the pronunciation of a native Japanese word

kanji

(education) The 1,026 kanji taught in primary school; a subset of 常用漢字 (じょうようかんじ, jōyō kanji)

smaller kanji historically used as a pronunciation guide, similar to modern furigana

kanji approved for regular use by the 文部科学省 (Monbu-kagaku-shō, “Japanese Ministry of Education”)

Sino-Korean vocabulary or "Hanja-eo"

The iteration mark 々, which indicates that the previous kanji ought to be repeated.