Plus they also only meet again are 10 years apart from each other. So it's not like they were around each other while shin was turning in to an adult or while in early adulthood. So I think this is perfectly fine and actually adorable that they met after all that time (not on purpose) so it was fate.(≧∀≦)
I don't see anything wrong with age gap unless there's a grooming involve. And it's a matter of preferences dude, if it's not ur cup of tea then don't read it. If it's weird and it makes you uncomfortable, don't read it?
You saw how their dynamics unfold. As far as anyone knows, their romance didn't even start when they were a minor so what's up bro? You're making an issue out of something that doesn't even have any problem. You're preaching bro
I can't get over the age gap...