Riya Narukawa is a freshman in high school with extraordinary talent for playing the violin, but he also struggles with mental health issues. Riya has dissociative identity disorder, which makes him appear perfectly fine and good one day, while on another day, he can transform into his complete opposite. There are "two" Riyas; he refers to his other self as his brother, believing that this brother resides within his body and forces him to play the violin. These two identities are known as Black and White. The multiple personalities cause Riya significant complications and distress, but when he meets Atsushi, it seems that his life begins to change.
Later in the manga, Saki, Riya's cousin, explains to Atsushi that Riya has been abused by his father since childhood. When Riya was in middle school, he and his friend Yasui ran away from home to escape Riya's father. Unfortunately, Yasui was hit by a car and sustained a broken arm, preventing him from playing the violin. Enraged, Riya's father beat him severely, causing him to lose consciousness and be hospitalized. Upon waking from his concussion, Riya seemed like a completely different person. The incident with Yasui and his father appeared to have triggered his split personality.
(Source: Mangafox)
