Won't You Keep Me Forever?

Rei Kanzaki, an elite white-collar worker, and Toma Saeki, a high school math teacher, are a working couple who have been together since college. They are, by all accounts, perfect lovers. But though Rei might seem like the world's most perfect man, and Toma might seem shy and hesitant, their personalities in the bedroom are a whole other story... (Source: MangaPlaza)