Kanato's childhood was kinda.... Um. I'll let wikia explain thus shit
Kanato was born the middle child of Cordelia, and raised alongside his two brothers, Ayato and Laito. Unlike Ayato, he and Laito were given more freedom, yet the former did not receive enough attention from his mother that a boy his age required. Cordelia, who referred to him as her "Little Songbird", often called for him to sing to her, which he was happily inclined to.
Kanato as a child craved his mother's attention and would self-harm just to get her attention though these efforts were largely in vain. Kanato did love Cordelia as a child however, this never reached her because she shows zero interest in him aside from his singing which sexually aroused her.
Kanato received his Teddy bear from Cordelia which she received from one of her lovers but had no need for. He prefers not to play so much with his brothers and remain alone with his only friend - Teddy.
He has been murdering living people and making them into 'dolls' since he was a very young child. Cordelia encouraged this behaviour stating she loved his dolls and thinks he should make more. Many of these dolls were his mother's lovers once they were of no further use to her.
When he finds Cordelia's bloodied corpse in the rose bushes (upon being pushed from the balcony by Laito) he burned what remained of her, laughing as he did so and put her ashes inside Teddy.
ANIME HUB NUMBER 3: Kanato Sakamaki!!!! Kanato is my little bipolar babe.
He always carries around his Teddy with him and frequently speaks to him. I know he seems weird but is still love him.
He is bipolar so some times he can be a total little shit. (But he's my little shit) and other times hes a cry baby that must be protected.