Keiichirō is a young man living alone, emotionally withdrawn yet not antisocial after his family died in a car accident while traveling to one of his live band performances. This traumatic loss led him to abandon his musical aspirations. He regularly prays for his deceased family, reflecting his religious nature, and lives a life of solitude marked by reflection on the past.

Seeking shelter from rain near a trash heap, he discovers an inactive android girl. Though a technician declares her outdated model beyond repair, prompting Keiichirō's initial decision to discard her, he has second thoughts and takes her home. The next morning, he finds her functional and preparing breakfast. He names her Flower, inspired by the sunflower she held when found.

Learning Flower suffers from short-term memory loss due to deterioration, Keiichirō provides her with a diary to record daily experiences. Over subsequent weeks, he gradually opens up while teaching her about the world, indirectly sharing details of his own history, including his family's tragedy and abandoned music. Their interactions begin to reconnect him with his capacity for connection and purpose.

Flower expresses a desire to see the ocean, having only witnessed it on television. This shared experience, coupled with her ongoing deterioration, catalyzes Keiichirō's emotional journey, compelling him to confront his grief and loss. While Flower's specific outcome remains ambiguous, their bond facilitates his progression from isolation toward acceptance and forward movement. The relationship becomes a mutual healing process, with Keiichirō's unresolved trauma finding resonance in Flower's fragmented existence and innocence.