
I hate to break it to you but manga/ yaoi about a minor uke and adult/teacher seme exist and some of them are actually pretty good, illegal, but still nice to read, if you forget for a sec that the uke is a minor ofc. And I dont think you could report this to the police but maybe poste a review on websites and theyll take down the manga, which is not very likley-
ps: When im talking minor sometimes its a 17 yo BUT i also read some where the uke was like 15 and the seme like 35 so................... and I think there still up on mangago( ̄∇ ̄")

It's a personal taste of mine, I think is morally wrong to a teacher date a underage student , in real life those kind of relationship can get abusive usually because the teacher has powers over a student (he can trade sexual favors for grades, for exemple) and a older person dating a teenager may easily manipulate them because lack of maturity. I get bothered thinking about those kind of things, makes me remember an old teacher that I had on high school who liked to 'compliment' my legs and my face but I was too naive back then to notice that was a sexual harassment, and talking about it a few years later with my girl friends from high school a lot of them had similar experiences with others teachers. I guess is kind of a trigger? gladly in this case the main couple has a very health relationship, thats why it is good for me.
So good, a health realtionship between a student and a teacher that doesn't feel abusive, the student isnt a minor so there s nothing illegal, and they're cute togheter. Amazing!