Oppai is a direct translation of breasts into Japanese, though it is used as slang in the same way tits or boobs is used in English. The term became popular in English with the rise of manga cartoons, online games, and anime shows in the West during the s—90s. In these contexts, oppai most often refers to disproportionately large, impossibly round breasts. People using the term oppai in an English sentence are most likely referring to a character in a Japanese manga, game, or anime. The two connotations coexist in Japanese, whereas in English, oppai is almost exclusively used as slang.