(botany) the seed of blackberry lily (Iris domestica), notable for being jet-black / a Japanese sweet made with 求肥 (gyūhi) wrapped in red bean paste, and sprinkled with white sugar

to use one's head

a deposit (oney given as an initial payment) or down payment (payment representing a fraction of the price)

金玉: (vulgar) balls, nuts

(idiomatic) to get mad; to be highly offended; to get pissed off; to get angry; to lose one's cool

(idiomatic) to be sharp; to be keen; to be on the ball; to have a mind like a steel trap; to be clever

Alternative form of 頭がおかしい

(idiomatic) insane, crazy, nuts, out of one's mind

iridescent; having different colours when the angle of view or illumination changes / ambiguous or vague; using weasel words

(slang) a forgetful person