Caligula no Koi: Side Master

High school student Kiyotaka Doyama is working as a master in the SM-Club "Basement." On a whim, he decides to get involved with one of the guests. When this regular turns out to be teacher Makoto Naruse, surprise and delight are equal—on both sides. Slowly, a unique romantic relationship develops. After his graduation, Kiyotaka showers Makoto with love, but as Makoto is busy at work and cannot meet him for a while, Kiyotaka gets irritated.

(Source: Gentosha, translated)