Koku

As a skilled violin craftsman apprenticed to Lily’s father, this central figure from B: The Beginning hides a dark, supernatural secret. He possesses the terrifying power to transform into a winged, heteromorphic entity. Beyond his craftsmanship, he is the mysterious culprit known as Killer B, a moniker earned from the cryptic way he leaves the number "13" at his crime scenes, marking him as a pivotal force in the series' unfolding mystery.