Where does “乃” come from?

乃 (Japanese) comes from Japanese の, from Old Japanese の, from Middle Chinese 能 — talent, ability.

Ancestry of “乃”, step by step

StepLanguageWordMeaning
1Japaneseのgenitive case marker; nominative case marker in a...
2Old Japaneseのplain, field
3Middle Chinese能talent, ability
Every word from Middle Chinese 能 →Every word from Old Japanese の →Every word from Japanese の →