A group of onmitsu, government-employed undercover agents, established by the 8th Tokugawa shogun, Tokugawa Yoshimune (1684–1751). Sometimes described as ninja.

one day, 24 hours / the daytime, the period from dawn until dusk / (figuratively) a short period of time / one day, someday, an unspecified day / the first day of the month

a birthday

regular day off (e.g. closed every Monday)

the twentieth day of the month / twenty days / Short for 二十日鼠 (hatsuka nezumi): a house mouse

幾日も幾日も: day after day

a lucky day, auspicious day

(rare) one's birthday

Saturday

the first day of the month (solar or lunar calendar)