black key (of a piano, etc.)

white key (of a piano, etc.)

(Internet slang) protected account (on social media, especially Twitter and Instagram)

to lock (a door, etc.) / (Internet slang) (of a SNS account) to change privacy setting to limited people and posts and/or profiles can be seen by limited people.

(idiomatic) to hold the key (to)

ice cube (small piece of ice used for cooling drinks)

Synonym of 黄昏 (tasogare, “dusk; twilight”) / Synonym of 黄昏時 (tasogaredoki, “dusk; twilight”)

(Buddhism) think on the power of Kannon

(literally) know the other side and yourself, a hundred battles will not be perilous