Responses
He was a cram school teacher not an actual teacher if I remember correctly so she could have very well been 18 and prepping for college exams.
She had mommy issues and grew up with only having a father figure so she was attracted towards older men. These issues don't justify her mistreating and purposefully traumatizing a child only to show up years later and then try to gossip about him as an adult when he never blamed her for how fucked up he became.
But since we don't know everyone's ages anything on the subject is just speculation.
At the end of the day, it's fiction. Who tf cares.
The story was hot but I didn't like Shirotani's father. He was sleeping with a school girl, even though he was way older and also his teacher. And they make it seem like the girl was a bitch (she kinda is towards little Shiro but YK, traumatized kids often traumatize younger kids, she was very obvious groomed and looking for approval) but never adressed the grooming his father inflicted towards her. Like she is annoying but he is a predator and that is way worst. Or how she is old now and never found any sort of justice but everything is ok because she still is a bitch. And at the end, Shiro contacts his father again after many years in this scene that is supposed to be emotional (?), as if nothing happened, as if he wasn't sleeping with a minor, as if the past didn't matter. IDK feels kinda simplistic and gross...
Like you can have mature themes in your manga, but at least be consistent FFS