Transfer student from Devil’s High School

After being reincarnated into a demon through time travel, there is also a sister-in-law, Rias, who claims to be a high-ranking demon, who often attacks her at night;
Akeno Himejima, who is also a servant, always wants to reproduce with him;
in order to avoid being overwhelmed by her body, she is even more meticulous. Life, work hard to improve your strength.
Can you become stronger by signing a trade contract with a human? Then sign it!
Mai Sakurajima, the Nakano family quintuplets, Killer Joel, Megumi Kato…all signed!
In order to live a peaceful daily life with the harem, Long Yi, as a devil, said that he still needs to work hard, either he is “invincible” in the world, or he is “invincible” in the world.