Miyo Sasaki, nicknamed Muge and adopting the cat identity Tarou, is a junior high student living in Tokoname. Her name "Miyo" combines "beautiful" and "generation," while "Muge," meaning "infinitely mysterious," originated from elementary school teasing after her mother left. The surname "Sasaki" signifies "bamboo grass" and "tree." At school, Miyo displays an energetic, rambunctious personality, openly expressing emotions and performing attention-seeking acts like the "Hinode Sunrise Attack" to pursue classmate Kento Hinode. This exuberance masks deep trauma stemming from her biological mother's abandonment and her family's subsequent restructuring. Resentful towards her father and stepmother, Kaoru Mizutani—whom she formally addresses as "Ms. Kaoru"—Miyo emotionally detaches from disliked individuals, viewing them as "scarecrows" to avoid hurt. She avoids family interactions at home, paralleling the aloofness of her stepmother's cat, Kinako. Following a confrontation with her mother during a festival, Miyo receives a Noh-style cat mask from a mysterious Mask Seller. This mask enables her transformation into a white cat with blue eyes and light brown facial markings. Adopting the cat name "Tarou"—bestowed by Hinode after his deceased dog—she uses this form to escape family tension and secretly bond with him. As Tarou, she listens to Hinode's troubles about his family's pottery shop closure and academic pressures while hiding her human identity for fear of rejection. This double life blurs her perception of reality, confusing fantasy with actual events when recounting experiences to friends. A turning point arrives when bullies publicly read Miyo's love letter to Hinode, provoking him to declare hatred for her "pushy" behavior. Devastated, Miyo relinquishes her human face to the Mask Seller, choosing permanent life as a cat. Trapped as Tarou, she regrets this decision after overhearing Hinode express remorse and witnessing her family's distress over her disappearance. Her stepmother's cat, Kinako, takes Miyo's human face to extend its own lifespan, thwarting Miyo's efforts to revert. Journeying to a mystical cat island, Miyo encounters former humans filled with regret for abandoning their lives. With Kinako's aid, Hinode follows using a partial cat transformation. After confronting the Mask Seller and nearly losing her humanity permanently, Miyo reconciles with Hinode, who reciprocates her feelings. Kinako returns Miyo's face, restoring her human form. This experience resolves her familial estrangement: she accepts her stepmother, repairs her relationship with her father, and stops emotionally isolating others. Hinode likewise openly pursues pottery. Their renewed bond culminates in Hinode initiating the "Sunrise Attack" toward Miyo, mirroring her earlier gesture and symbolizing mutual understanding.