The other day, when I was reading an adult book, I thought, "I can tell whose breasts they are by just looking at them. Well, am I a king of oppai (boobs)" However, there was no way to prove it.... But one day, I receive a letter and it includes a bunch of free sex tickets! Also, the reverse side of each ticket has the photo of someone's breasts. When I'm confused, a girl, Nil, appears in front of me. According to her, I'm qualified to take part in a game. It seems the tickets aren't fake. My mission is to look for a girl who's got the same breasts printed on the ticket. Like this, my search for oppa(boobs)i begins....