Oresama Tengoku! Rojiura no Ningyo

From Attractive Fascinante:

The club manager, Kagami, saved a pretty guy, Ran, in a middle of a rainy night. Kagami couldn’t stop himself to devour the beautiful Ran after taking him back. Ran accepted Kagami and also learned whatever Kagami taught him. But where does Ran come from and how is he related to Kagami?