A Mastermind? No, I'm just the Live-In Son-in-Law - Chapter 128: Proof

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.

In the year 298 from the era of the gods, elementary school girls Sumi Washio, Sonoko Nogi, and Gin Minowa are tasked with an important mission. They are to become heroes and fight Vertex, a mysterious enemy that is attacking Shinju-sama, the god tree that protects Shikoku, the only area in the world that is still habitable. What they don’t know, is that this fight will cost them more than they could have ever imagined.

“I Possessed the Academy’s Silver-Rank Examiner.”I was on the verge of becoming someone who’d be pushed around by students left and right…◎ [Silver Gatekeeper]“No one can pass without the Gatekeeper’s permission.”I awakened an absurdly overpowered trait.TN: This novel follows a protagonist who becomes a rank examiner, tasked with evaluating students at an academy to determine whether they are worthy of advancing from Bronze to Silver rank. Known as the Silver Gatekeeper, he has the authority to decide which students can progress. As a gatekeeper, he possesses overpowered abilities, making him powerful when fighting on the examination field.