The story revolves around Nayu Hayama, who embarrasses herself on the first day of middle school by accidentally showing her adult panties. As two other students, Yako Jingūji and Haruka Shiraishi, hear rumors of her engaging in "enjo kōsai", or compensated dating (which often is viewed as being close to or the same as prostitution), they investigate. They soon learn that Nayu is an 'underwear monitor' who tests new underwear products, and has great insight on what underwear people should wear. Nayu hopes to help everyone get through the vital stage of their life by opening an underwear club.

At Hekiyo Academy, all but one of the Student Council members are elected via popularity contests, and those seats are filled by the school's most beautiful girls! The lines between fact and fiction disappear at the STUDENT COUNCIL'S DISCRETION!

Kaiji Itou is a good-for-nothing loiterer who spends his days drinking beer and stealing hubcaps—that is, until he ends up being tricked by his former co-worker. Unable to suddenly repay his friend's huge debt all by himself, Kaiji is offered a shady deal to participate in an illegal underground gamble on a cruise ship. This turns out to be nothing more than the beginning of his new life of hell—thrown headlong into a life-threatening roller coaster of mind games, cheating, and deceit.

Nangou is a compulsive gambler who has accumulated debt over three million yen. In a last ditch attempt to clear his record, he decides to wager his life on a game of mahjong with the mafia. Unfortunately, as the game progresses, Nangou only moves further from the prize and closer to death. When all hope seems lost, the game parlor is suddenly intruded upon by Shigeru Akagi, a young boy on the run from the police. Desperate to turn the game around, Nangou hands the game over to Akagi after teaching him a few of the rules. The mafia can only smirk as Akagi sits down to play. However, they soon come to learn that Akagi is a natural born gambler. An imposing figure who does not fear death. One who is destined to become a legend.