Marujirushi

An O mark, also known as Marujirushi (丸印) in Japan and Gongpyo (공표, 空標) in Korea, is the name of the symbol "◯" used to represent affirmation in East Asia, similar to its Western equivalent of the checkmark. Its opposite is the X mark ("✗") or ("×").

The hanamaru (花丸^?) is a variant of the O mark used in Japan, written as ...
Wikipedia