Everyone in his Yakuza gang looked up to him. He was the boss's favorite pupil, but then in a single night, after he had won so many territorial fights for his gang, he lost everything! Why?

It's been several years since "dungeons" appeared all over the world. Ryosuke Mizuki, a company slave, is present at the scene where his workplace was swallowed by the dungeon and gets the cheat skill “Ski...