Kouta Hasegawa is an entirely ordinary high school student who cherishes his Pompompurin plush toy, a Sanrio character based on a Golden Retriever, which his grandmother gave him in his youth. However, an incident where other children accused him of being girly for his fondness of Sanrio characters made him feel ashamed of his attachment to Pompompurin. Through a series of unexpected events, Kouta ends up meeting others at school who also like Sanrio characters—Yuu Mizuno, a flashy boy who is popular with girls; Shunsuke Yoshino, a member of the soccer team; Ryou Nishimiya, an underclassman who works as a library assistant; and Seiichirou Minamoto, the student council president. Through his new friends, Kouta learns that there is no need to be embarrassed for liking Sanrio characters; and together, they aim to create a play for the cultural festival in order to transform his normal school life into a sparkly one.