楷
カイ

square character style, correctness

JLPT0 G7 S13 F5000

As per 皆# (line up) + 木 tree/wood → lacquer tree, with aligned (pinnately compound) leaves → *model*; *standard* (← orderly alignment) → *block style* for writing Han/Chinese characters (regarded as the standard form).

[Full Kanji Etymology List]