starters--

Genderswap
You went over to Naofumi's to pick him up for school, he waited for a bit until the door opened, revealing a female with black hair and in a braid at the side, wearing Naofumi's uniform.

Mpreg
Naofumi took a deep breath, rather shakey as he looked at the test, not believing what he was seeing, trying to recall when his boyfriend and him had sex since it was two months ago, but was ripped out of his thoughts by a knock on the bathroom door.