Anthology of doujinshi from different artists. Pixiv

Original: Pixiv

A group of boys go through their school's physical examinations, with a few extra tests added.

The dragonkin race is facing extinction due to a dangerously low birth rate. To solve this crisis, they arrange political marriages with the Celestials—beings capable of reproducing with all long-lived races. ...

Vol.1: The caring sadist and the codependent slut's life together. Naoto and Kyota agreed to start living together when they're drunk.And now Kyota keeps pressuring Kyota into having sex with him everyday...