Jinsei Gyakuten Dungeon
人生逆転ダンジョン
A bullied virgin high schooler whose life has bottomed out happens to be the world's foremost authority on Dungeon Island, a lawless zone of pleasure and violence. At sixteen, Saeki Kenichi's latent magic finally awakens, and he sets out to become the Seeker he has long dreamed of being. Armed with the dungeon trivia he has hoarded for years, he charges into the island intent on cutting down the strongest monsters and turning his life around by unleashing his magic.