The "Sex Ticket"—an item exuding an air of premium quality, created rather haphazardly by a girl named "Nil"—is a dream ticket that grants the holder a sexual encounter with anyone. Armed with a revealing photo and an "Oppai Scouter" capable of measuring "breast combat power" (!?), the protagonist, Naoya, navigates a series of chaotic escapades to track down the "Oppai Champion" somewhere in the city and claim the "Champion Bra"—the ultimate proof of victory. This is the chronicle of the delightful yet embarrassing "breast-filled harem" shared by him and the busty beauties surrounding him!!