Mike-Chan To Kuro-Sensei summary:

The worries of a virgin teacher nearing his thirties, “Is it okay if I’m the only one being doted on!?” A bright popular honor student x a kind and admirable math teacher. ーー A math teacher who is well-liked by students for his warm personality, Kusunoki. His lover is the most popular in class, Mishiro. Just when they were thinking about having sex, they both wanted to be bottoms with no experience topping! At first they used their fingers to tease, but as expected, their butts became lonely!? Also, a compilation of short stories about a couple having see-through sex in the bath and a love that began with sex on the road.