that sometimes happen in shoujo manga.
japan actually pretty strict with age relationship, if a police saw an adult with a minor who isnt family, the adult will be questioned, fined, jailed etc. however the age of legal adulthood there is 20... so the older girl isnt considered legal... they are both minor in japan. so that's probably why it can still make a cut in a shoujo manga, or maybe this isnt a shoujo manga idk

So are we not gonna talk about how the lady who is 19, NINE-TEEN, slept with a 16, lemme spell out out SIX-TEEN year old and thats not even their first time. He was in MIDDLE SCHOOL and she was in HIGH SCHOOL when they first did it... Not only that but the girl who's friends with her KNEW, and didn't do anything. Bro what the fuck.