Kato has spent his miserable working life enduring the abuse of an overbearing older boss at a black company. But when that same boss pushes him from a train platform, Kato's life comes to a sudden and violent end. He awakens in another world as Cain, a young nobleman, and discovers that he's been granted a very unusual ability: he can identify troublesome and abusive “old-timers” simply by looking at them, complete with a numerical level showing just how harmful they are.

After everything he suffered in his previous life, Cain has no intention of letting people like that run rampant ever again. Whether they're corrupt nobles, arrogant authority figures, or self-important elders abusing those beneath them, anyone whose “Old-Timer Level” gets too high had better watch out! Armed with the power to literally measure how much trouble someone causes through their age and authority, Cain sets out on a cathartic otherworldly crusade to deliver divine punishment to every rotten old-timer he encounters!