Gray to Blue no Ai Made
Not your usual bl that's for sure. The age gap has to be one of the biggest I've ever seen but I kinda appreciated that the author didn't sugarcoat it by making the old man look younger. The characters are simple yet interesting (and kinda realistic too), I liked that the teacher wasn't involved in their relationship as a love interest cause that would have totally ruined the flow of the story. Was I uncomfortable seeing an old man get it on with a high-schooler? Yes very, and it would have all worked better for me if the age gap was a little less extreme (like an uni student & a man in his fifties maybe?) cause him being in high school was pretty fucking weird. Literally everything else was good and well written, no complaints.
Konya Mo Kimi Ni Gochisousama