Miyako Hoshino, a college student who is shy with strangers, becomes oddly smitten when her little sister Hinata brings home her classmate Hana Shirosaki, but doesn't make the best first impression with her. When Hana returns for a sleepover, Miyako has Hana dress up in cosplay outfits she made, offering to treat her to as many sweets as she wants if she keeps doing so. The next day, as Miyako secretly tries on her cosplay herself, she is spotted by her new next door neighbor, Noa Himesaka.