"Yeah, I don't think there need to be any charges. Not even against the 23-year old teacher who's been with one of his 16-year old students for 2 years, and got her pregnant. It's not like that's a crime, right?"
*rolls eyes*
@KelpTheGreat Actually, it's not. The age of consent in Japan is 13. The law further states anyone age 13-17 cannot legally partner with anyone 18 or older, but that also has a clause stating that it is legal so long as they are in love.
Judge this law all you want, but in Japan there was nothing illegal about that relationship; or, at the very least, nothing they could prove.
However, many prefectures also have local "corruption of minors" or "obscenity statutes" which raise the de-facto age of consent to 16-18, unless they are in a "sincere romantic relationship", usually determined by parental consent. For example, the effective age of consent in Tokyo by local statute is 18.