Hakuto, a 29-year-old NEET, discovers a mysterious gemstone in the trash that grants him a sinister transformation: a tentacle monster wielding shadow magic. With newfound power, he begins seducing the city's Magical Girls—a fame-obsessed idol, an envious older sister, a melancholic queen—converting them into his devoted followers and building his dark harem. Yet corrupting magical heroines proves far more complicated than expected. Between managing his growing collection of superpowered servants, orchestrating team activities, and mediating their constant conflicts, Hakuto finds himself playing unwilling administrator to his own supernatural empire. The chaos of leading five volatile girls through jealousy, bonding, and intimacy becomes more demanding than any corporate job, with emotional complications he never anticipated. What began as a power fantasy transforms into something far messier: genuine relationships built on corruption, possession, and twisted devotion. **Content Warning:** Explicit sexual content, harem dynamics with five characters, group scenarios, corruption themes, reproductive content, and romantic physical affection. No NTR. Minimal tentacle-specific content despite thematic elements.