Eleven-year-old Natsuru Nanao is the ace of the soccer team, yet has trouble speaking to girls because of a certain event following his transfer to his current school. Due to his father dying long ago, he lives only with his mother but doesn't let this distract him from his passion for soccer, as he hopes to become a professional player. One day, a female classmate named Rio Suzumura approaches Natsuru, a meeting which signals a huge turning point in his life.
Upon talking with Rio, Natsuru immediately becomes interested in her. After he saves an abandoned cat, he runs into the girl and her younger brother Yuuta on their way to the supermarket and asks if they can take care of it, to which they agree. But when Natsuru arrives at their home, he is shocked to discover that the siblings have been living alone in a dirty house, a secret which Rio absolutely wants to keep. As Natsuru spends more time with them, their circumstances and reason for secrecy are slowly brought to light.