Doomsday: I Am the Beginningless Demon, and Yukino Is Coming After Me

He transmigrated into an apocalyptic crossover world overrun by demons, brought about by Kibutsuji Muzan.

He became the First Demon, Shimu Zan, born ten thousand years before Kibutsuji Muzan, and took the alias Su Wu.

His abilities were more complete than Kibutsuji Muzan's.

He was also bound to a Get Stronger by Pretending System.

So he pretended to be an upper-class gentleman, living in luxury with his wife, Eri Kisaki, and daughter, Ran Mouri.

He also adopted Anya, who could read minds.

To become even stronger, Su Wu pretended to be a student at Sobu High School.

He never expected some students to awaken a Human Nature Choice System:

Yukino: Make Su Wu sleep with you within thirty days, and you'll get the Water Breathing First Form!

Yahino: Please save my sister Yukino, who's trapped on Spider Mountain. Reward: Flame Breathing Second Form, Second Form.

Meanwhile, Su Wu's power soared. P.S. This is an apocalyptic crossover story.

This novel and its characters are entirely fictional. Any resemblance to real people or events is purely coincidental. Do not imitate.