Nanako Gyoen entered the prestigious Seiran Girls' Academy and began her high school career, where she met the school's celebrities, Kaoru Orihara and Rei Asaka, and became friends with them. For some reason, the president of the "Girls' Youth Club" that all the girls in the school aspire to join, Ichinomiya Ruko, took extra care of Nanako and invited her to become a member of the "Girls' Youth Club", which also aroused everyone's jealousy. Rei's pain, Kaoru's bitter smile, and Ruko's unpredictable attitude all originated from Nanako's letter to her brother.