High school student Naoto Watari lives with his younger sister, Suzushiro, at his aunt’s place. After his parents’ death, he gives up everything to take care of his sister. But one day, his childhood friend Satsuki Tachibana transfers to his school, and Naoto’s quiet life is turned upside down. Satsuki’s wild actions foreshadow a storm in Naoto’s life and his relationships with those around him.