Longevity starts from having a daughter in old age - Chapter 51 - 41 Leaving i

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.

Crimson Vale Academy—where reputation is currency, and failure is a stain you wear on your sleeve.Behind gothic walls and spotless uniforms, students aren't just educated—they're measured, ranked, and pitted against each other in a brutal meritocracy. Privileges are earned, not given. The strong rise. The weak vanish.Enter Kairon Vale, a transfer student marked Rank D—the bottom of the bottom. No badge. Just a stitched black fang, branding him as “Obsidian”—a warning to others.In a system where points dictate your value, Obsidian-ranked students claw for every opportunity to ascend into the prestigious Golden or Platinum ranks—where comfort, power, and influence await. But for most, it’s a losing battle.Yet Kairon isn’t here to fit in, impress, or play by their rules. Cold, calculating, and impossible to read, he watches the system… and waits. Because while the academy judges worth by numbers and names—he understands something deeper:Everyone wears a mask. And every mask can be cracked.Let the games begin.

The “S-rank Hero Factory” that raised 1,000 S-rank heroes.

The graduates’ manufacturing machine.

The strongest support.

These are all words that refer to me. But could this actually be the world of that game?

To survive, the unfortunate Gong Qiying, who became the lord of the Sein Dungeon, had to make his dungeon extremely “hellish”:Doors that “cannot be opened from this side”,treasure chests “triggering teleport traps”,a three hundred and sixty-five mile journey from the starting point to the BOSS room with no place to rest,monster knights with great bows on either side of a narrow bridge,and sinister ambushes around corners.There's also unavoidable visits to poisonous pits and hidden paths...Additionally, well-known fighters like Isshin Ashina, the Furnace Knight, Rajang, and the Scourge Legion bring unexpected surprises!Various unique rewards such as the Flaming Sword, Murky Hand Scythe, Rapid Slash Longsword, Sacred Oath, and Flame Empowerment will make you too happy to contain your joy!Gong Qiying: The most important thing in my dungeon is to ensure adventurers have fun!