She was a devoted sister. More than anyone else in this world──

Nagisa Arahama, a second-year high school student, had a beloved younger brother. Her younger brother, who believed he was a girl. Her younger brother, whom she cherished most in the world. Her younger brother, whom she lost to suicide last June. From that day on, Nagisa’s every day turned gray.

But even then, Nagisa fell in love. Her gray days finally regained their colors.

However, Nagisa still doesn’t know. How distorted her feelings for her younger brother truly were. The depth of the darkness in the hollow hole that had opened in her heart.