Sanada Yoru, a scarred high school guard haunted by a childhood stolen by terrorists, thought he’d finally found peace patrolling the gates of a quiet Japanese academy. Then darkness swallowed them all. Awakening in the depths of a succubus dungeon, Yoru and his students face a cruel trial: the men must conquer monstrous floors as testers for an otherworld invasion, while the women—classmates, teachers, beauties one and all—are auctioned as s*aves, their fates sealed by glowing ink tattoos of absolute obedience… or merciless disposal. Armed with battle-hardened instincts and unyielding resolve, Yoru fights alone, claiming his harem one bloody victory at a time. But as bonds deepen and otherworldly temptresses join the fold, can he conquer the dungeon’s heart—and save them all?