Start by Spending One Billion [Entertainment Industry] - Chapter 45

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.

I am merely a reviewer, albeit the products I review are slightly different. For example, I review quantum computers, artificial intelligence, anti-gravity mech armor, planetary engines, sublight colonial ships, stellar detonators, etc…

Feng Yun was an ordinary young man who was unable to cultivate. One day, He got the inheritance of the Ancient Yang Demon Clan and a mysterious sword. With these he became a super genius and started his new journey from a small town to heaven, sweeping across the world, vying for the supreme existence.