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

kanji

(orthography, historical) tōyō kanji (kanji that were declared official by the Ministry of Education of Japan on November 16, 1946, later replaced by 常用漢字 (jōyō kanji))

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"

Alternative spelling of 漢字返し

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

(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)

kanji not approved for regular use

Kanji characters outside of the jōyō kanji and jinmeiyō kanji lists. For example, 攪.