Tadashi Momose becomes the 13th tool for the enemies after a symbiotic connection evolving over six millennia, assuming the new identity of 'Momoe' through unwanted alterations by extraterrestrials and a mysterious syndicate. Fused with an alien entity, he undergoes a transformation into a hermaphrodite possessing dual reproductive features. His unique ability involves using his seminal fluid to influence human minds, converting them into obedient drones under his command. Through deploying parasites into hosts like Midori, Yuki, and even the student council president, he expands his loyal circle as needed.