Amu, a big-titted member of a music circle, had long been targeted by the three male members. After a drinking party, they lured the drunk Amu back to their place. She happily followed along, and they kept drinking while playing games to amp up the mood. Testing her reactions with body contact, they noticed she responded with pleasure, so they continued touching her freely, making her completely submissive as all four indulged in an erotic session together.