The story of HHH Triple Ecchi revolves around Makino, a high school student who unexpectedly becomes the manager of the 'Public Morals Alliance,' a club that is ostensibly dedicated to maintaining discipline but is actually a front for the sexual misadventures of its three beautiful and domineering members: Satsuki, Kanna, and Fumi. Each episode follows Makino as he is drawn into their increasingly audacious and lewd schemes. Satsuki, the student council president, uses her authority to create situations where she can dominate Makino. Kanna, a seemingly innocent and shy girl, reveals a surprisingly aggressive and exhibitionistic side, while Fumi, the mature and seductive school nurse, uses her position to entrap him in her office for 'check-ups.' The series follows their dynamic as Makino is subjected to their constant and escalating desires, exploring themes of domination, submission, and public exhibition.