MTL - Study Days at Hogwarts - Chapter 1120 Suicide

After dying in an oddly anticlimactic vending machine accident, Kazuki Ren is reincarnated in the demon realm—not as a hero, not as a villain, but as the only human male student enrolled at the mysterious Academy of Ruin, a school where all the professors are demon lords and all the students are powerful, beautiful she-demons.Ren is told he has one task: survive.But there’s a catch. The Academy’s darkest secret is about to awaken, and Ren holds a hidden power that could either destroy the demon world... or rule it.Now surrounded by seductive demons with hidden motives, eldritch tomes, forbidden dungeons, and twisted exams, Ren must master his ability—or be consumed.Magic, mystery, danger, and temptation await in this dark academia harem fantasy.

The legendary Qin Chen from the Tianwu Continent accidentally fell into the Martial Domain because of his friend’s betrayal.

Three hundred years later, he was reincarnated on an illegitimate son of the royal palace who had been bullied.

He used his previous life accomplishments, concentrating on his skills, refining the pill, and rising against the sky, rising strongly, and embarking on a shocking journey that shocked the mainland.

- Description from MTL

I was a genius in the Earthen Plane.