From what I understand, Toru killed himself. Natsuno (silver-haired) lived and is the one narrating the story.
Agree with shinsekie. At the end, it is revealed that Natsuno was, in fact, not dead, but Toru kills himself in despair. Natsuno later wakes up and finds that Toru is dead. Even though the POV for narration isn't that clear to me, at the end he says that his hair (called Toru's "sparkling treasure") had "darkened with despair and turned the same color as Toru's," which explains the hair color confusion.
Talk about Romeo & Juliet comparisons...
I got it now! Thank you both of you <3
Can someone explain chapter 6 to me? Who was the one that commit suicide? Toru or Natsuno? And who was the guy narrating the story? Heeeelp