夕 is 月 (moon) with one stroke removed — the half-shown moon of early evening, not yet fully risen. When the moon is full up it is 月 (night); when it is just appearing it is 夕 (dusk). A delicate character that splits time out of the very same picture.

The characters that grow from 夕 are wonderful. 多 (duō, many) is two 夕 stacked — evenings piling up means "many". 名 (míng, name) is 夕 + 口 (mouth): in the dark when you cannot see a face, you call out a name with your mouth to identify someone.

Mandarin: xī, 1st tone. 七夕 (Qīxī, the 7th-night festival — the Cowherd-and-Weaver-Girl legend, China's Valentine's Day), 除夕 (chúxī, New Year's Eve night), 夕阳 (xīyáng, the setting sun).

Japanese: on-reading セキ (seki), kun ゆう (yū). 夕方 (yūgata, evening), 夕日 (yūhi, setting sun), and 七夕 (Tanabata) — the great star festival, read with a special native reading rather than the expected on-reading.

Korean hanja-sound "seok": 夕陽 (seokyang, sunset glow), 秋夕 (Chuseok). Korea's biggest holiday, 秋夕 — "autumn evening", the harvest full moon — carries this character.

Memory aid: the moon (月) with one stroke taken away — early dusk, the moon only half-risen.