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.
as Nayu Hayama
as Haruka Shiraishi
as Yako Jingūji
as Keigo Hayama
as Kiyono Amahara
as Hiroki Komachi
as Tamaki Mizuno
as Tsukamoto-sensei
as Yōko Sagisawa
as Principal
as Ōkuma-sensei
as Kōta
as Kaori Seto
as Komachi's older brother
as Tsuzuki
as Chigusa
as Tanihara-sensei
as Suzuki
