Masaharu Tsuwabuki is a kind but socially awkward high school student who struggles to fit into his new class. One afternoon he helps classmates Sumomo Akihime and Nadeshiko Yaeno with the gardening club. When he goes to buy juice, he collides with a masked man named Arthur, a servant from the magical world of Figurare, and their drinks are accidentally swapped. Masaharu unknowingly drinks a magical potion and transforms into a small stuffed sheep at night. A teacher, Natsume, enchants the plushie so Masaharu can still speak and move, but he learns the only way to permanently regain his human form is to collect seven magical Stardrops. Only a chosen girl called a Stellar Spinner can gather them. That girl turns out to be his classmate Sumomo, and Masaharu cannot reveal his true identity. Under the name Yuki-chan, he becomes Sumomo's plushie companion and helps her find the Stardrops under the night sky.

The story takes place across two connected worlds: the human world Retroscena and the magical world Figurare, where two competing magic schools, Pramu Clovis and Sentou Asparas, each send their top Stellar Spinner to the human world to collect Stardrops in a goodwill competition. By day Masaharu navigates school life as a normal boy, growing closer to Sumomo, Nadeshiko, and other classmates, while by night he experiences Sumomo's more private personality. The central narrative arc follows the pair's deepening bond as they gather each Stardrop, encountering other magical rivals such as the Prima Pramu and Prima Asparas, and confronting the mystery behind the potion that cursed him. Along the way, Masaharu's awkwardness gives way to genuine connection, and he must decide whether returning to normal is worth losing the special relationship he has built with Sumomo.