Responses
He wasn't 19 when he was his tutor if I remember correctly our guy is twenty when the story first starts and in college. And the doc is in his thirties. So there's potentially a 10 yr difference. The main guys friend said the doc was wrong for messing with a minor and tells him to tell the doc as his tutor to wait till he's 18 and when our guy tells him that he stops and leaves.
So he was a minor when he messed with him originally. They just didn't have sex. Or do much besides kissing. I think it was wrong and honestly I just choose to not think about it.

He was 19 years old when they met, and in Korea, anything under 20 is a minor
Personally, I get icked out when I see anyone over 21 going after anyone under 20 bc I feel like 18-19 year olds are still going through a lot of transitions so they feel like highschoolers to me even if they're technically legal BUT it's interesting seeing people call him a pedo for going after a 19 year old while usually the comments are so quick to say that 18+ is fair game, or to not have any reservations the second a character is 18
I mean regardless, it's kind of irrelevant bc it's 6 years layer when they're both grown as adults at 25 and 30+, plus it's fiction, but it's an interesting observation