A slim young man with yellow eyes, black hair combed back, (with a single lock that falls on his forehead), and a distinctive mole. Wears a tight fitting sleeveless blue shirt, a brown leather belt and black detached sleeves. Wields two spears, Gae Dearg and Gae Buidhe.
Do not confuse with Cu Chulainn.
Voiced by Midorikawa Hikaru.
True Name: Diarmuid Ua Duibhne