Koku, B: The Beginning Wiki

Koku is one of the protagonist in B: The Beginning. He works as a Violin Craftsman under Lily's father and has the ability to transform into a black-winged, heteromorphic being. He is also the true identity of Killer B, a name derived by his unusual way of writing the number "13" at his murder sites. Since the attack on Jaula Blana orchestrated by Gilbert Ross that took the lives of several of his classmates including Dr. Heath Flick, Koku has spent the last seven years in search of his love, Yu

Koku, B: The Beginning Wiki

Haru-ōji - Super Mario Wiki, the Mario encyclopedia

Yuna (B: The Beginning)

B: The Beginning - Zerochan Anime Image Board

B: The Beginning The Sequel - This Week in Anime - Anime News Network

Can you name any anime series with a mature plot? - Quora

Koku, B: The Beginning Wiki

8 underrated Anime for fans of thriller genre

Koku, B: The Beginning Wiki, Fandom

Samurai Champloo - Wikipedia