Slang. It's another way of say a girl became a woman or lost her virginity.
Dad: what did you do to my daughter? Boyfriend: her mermaid became moana. Dad: wym? Boyfriend: it's another way of saying a girl became a woman or lost her virginity.
Boys who enjoy yaoi (a genre in Japan that contains sexual and/or romantic relations between two men); literally translates to "rotten boy"; corresponding female : fujoshi