Second Heavenly Stem

It marks second place in an old Chinese sequence. The ten Heavenly Stems form an ordered cycle: 甲 comes before 乙 and 丙 after it. The stems counted days and marked ritual calendars; paired with the twelve Earthly Branches, a separate cycle, they form dates such as 乙酉.

Early forms appear on Shang-dynasty oracle bones—bones used for divination—and bronze objects, then in later seal, clerical, and regular Chinese scripts. In Japanese compounds, 乙 can mark a second category, as in 乙種. 乙女 means a young woman, while 乙な describes a distinctive, tasteful quality; these word meanings do not decode a bare post by themselves.

What does 乙 mean in Japanese posts?

It is casual shorthand for お疲れさま, “good work.” A 2010 study of Japanese online language on 2channel, a forum, and Niconico, a video site, records お疲れ→おつ→乙: a shortened greeting converted by a Japanese input method. In posts, it thanks someone for work, a thread, a stream, or useful help.

Around 2010, community examples also show the turn: after an accusation, 乙 becomes a dismissive “nice performance” jab, not thanks. A bare reply after someone’s effort reads as friendly more readily.

Why does 乙 look different?

Regional fonts can change its shape without changing the character. Chinese, Japanese, Korean, and other CJK fonts may draw 乙 according to local conventions. If its shape varies between devices, check the font or language setting before treating it as a different character.