Hikaru is asked by her childhood friend Ryota's parents to care for his grandfather, Kozo, who has lost the will to live after his wife's death. Around Hikaru, however, Kozo begins to smile again. Concerned for his health, Hikaru continues to care for him warmly and affectionately, like a true family member. Witnessing their close bond, Ryota grows increasingly jealous and frustrated, tormented by his unrequited feelings for Hikaru. Desperate to break them apart, he takes action—but his efforts only draw Hikaru and Kozo closer, awakening forbidden emotions. This story explores love, jealousy, and the complexities of human relationships.