E Eto and Y/n was born to Ukina and Yoshimura as hybrid human and ghoul beings. Because their mother had secretly been investigating the organization V, they forced Yoshimura to kill his lover as punishment for "betraying" them. In order to protect his infant daughter and son from them, Yoshimura entrusted to Eto care of a ghoul known as Noroi and left her in the 24th ward with thier mother's diary. It is unknown what exactly happened to Eto in the following decade, but Eto would emerge from the 24th ward as a kakuja and begin a bloody rampage. As for Y/n, Yoshimura ordered Noroi to leave him and let him die because, in Yoshimura's opinion, he only needed and wanted one child. Fortunately, when a single mother overheard a newborn sobbing in a box, she took the boy in despite being aware of the risks. I dont own toyko ghoul or song in this story # 2 in Eto