I can see why there aren't any coding tags.
Just how would you code this?!?!
Yes, it's ecchi.
I suspect psychological could also come into play.
Romance. Yes, romance would be appropriate, I suspect. Bizarre romance, but romance nonetheless; after all, both have confessed that they couldn't have this happen with anyone else. It will definitely draw two close people even closer together. Both psychologically and literally, I suspect.
Bibliophilia doesn't have a tag, unfortunately.
School? Slice of Life? Dunno.
Ah, codes are appearing as I type. Comedy, ecchi, school life. Clearly, this is still in the process of being set up.
Comedy. How did I miss comedy?
Anyway, this looks like it could be very amusing. And completely life destroying for them if anyone were to catch them at it. Which, of course, is part of what adds to the comedic dramatic tension.
@SilverHelios
Indeed, thanks.
The mangaka is new to me, I think I'll check out what else he has done. I've already tracked down his Twitter and Pixiv.