On Bossun's 15th birthday, he finds out the truth about his parents. Unable to cope with the tragedy, he lashes out, only to meet the child his father once saved when he was a kid, all grown up, who gives him a letter...
They'll be family, inheriting half 
of my blood and half of yours, Harue.
Será familia, con la mitad de mi
 sangre y la mitad de la tuya, Haru.
Eles vão ser uma família com metade
 do meu sangue e metade do seu, Haru.