After winning tickets to an old theme park on the outskirts of Tokyo, Casio and his friends brave the eerie rumors surrounding the place for a little winter adventure. However, what was supposed to be a fun day trip takes a horrific turn when one friend lures Casio away from the group—and stabs him to death. While he bleeds out, his friend tearfully begs him to save someone named Asebi. When Casio next awakens, time has rewound to the moment he set foot in the park that morning. Though he’s shaken and desperate for answers, his “second” day goes by without incident—until he tries to leave and snaps right back to that morning again. As he spirals into panic, a mysterious girl appears and introduces herself as Asebi. She tells him she’s been trapped in the park for a long time, reliving the same day over and over. Now Casio is caught in the loop as well…and according to Asebi, the only way out is to kill someone.

In my new world, life has no worth. Reborn as an apprentice under the Order of Assassins, an organization that takes on all manner of underhanded jobs, I’m prepared to do anything and everything to survive.

First, I have to get through their oppressive training, where failure equals death. My assassin-to-be rivals include a tigerborn whose strength eclipses my own, an elf who is a master of essence, and a dragonborn, their kind known as the mightiest of races. Isn’t all that almost unfair?

Although death lurks around every corner, I swear I’ll claw my way through this hell. Manipulating powerful foes and the adults around me, punishing those who stand in my way… If that makes me a monster, so be it.

There is nothing and no one I won’t tear down for the sake of survival.

Not a shred of morality sees the light in this darkest of fantasies.