Lost One's Weeping

Kaneki Ken is raised by his elder sister, Rize. She sends him to Anteiku to spend his summer with a close relative while she's busy with her "work." A week later, the purple-haired girl appears on the news dead. Kaneki is faced with finding who exactly murdered his beloved sister, all the while trying to unravel secrets about himself. AU where Kaneki is born a one-eyed ghoul.