Masu Mark

It reads ます (masu), usually replacing a polite verb ending.

The Japanese term 枡記号 means “masu symbol.” The square pictures the top of a wooden masu measuring box, with a diagonal bar for leveling grain. Masu vessels measured grain and liquids such as sake, oil, salt and soy sauce; they also figured in trade and taxation.

The Japanese measure word 升 appears in the Engishiki, an administrative code, in 927.

It began as a measuring-box rebus.

In the Edo period, Japanese shop signs put 〼 after an availability word in place of ます, turning a stock notice into a visual pun.

The same sign wordplay in the Edo period could double 〼 as 〼〼 for 益々 (“more and more”), an auspicious phrase about prosperity or happiness.

How should I read 〼 in a message?

Read it as ます unless the phrase points to the measuring box.

In an availability notice it closes a playful あります. Doubled before a prosperity word, it signals the 益々 pun. Alone in chat, read it as a deliberate masu flourish, not a command, reaction or checkbox.

Readers unfamiliar with the convention may mistake the square for a box or checkbox. Write out ます when clarity or formality matters.