night

necessity (quality or state of being necessary, unavoidable, or absolutely requisite)

unnecessary

needlessness

necessary evil

staying up late

(rare) a female given name

湯桶: A lacquerware container with a spout for holding broth or tea for consumption after a meal; a type of tea caddy shaped like a pail.

a hot spring one has discovered that he/she wishes to keep secret from others, a secret hot spring

men's bath (in a public bath)