Kairi

The birth rate is falling sharply in 21st Century Japan. To combat the decreasing numbers, there's only one option left: get men pregnant. Yuki and Ryu are chosen to test a new drug that makes conceiving possible for men and are randomly paired up for the experiment. Yuki has to have sex with Ryu every day, even though he doesn't like him. However, the experiment has a condition: you can't leave the experiment until you give birth to a child. Reluctantly doing their best to get pregnant, Yuki and Ryu slowly start growing closer,but their time's running out! Then there's a new and embarrassing experiment with a loving couple, Ren and Rui, that gets them in the middle of even more embarrassing action!

Youki was reincarnated in another world. However, instead of being reincarnated as the hero or the demon lord, he was instead reincarnated half-assedly as a minion of the Demon Lord. One day, the Hero's Party attacked the Demon Lord's castle with the intent of defeating the Demon Lord. Of course, Youki was able to repel their attempt with ease. In spite of this, he ended up falling for the cleric, Cecilia, at first sight...