Knell Hydra is a character from the anime Blood Lad. He is the younger brother of Bell and Fuyumi and the son of the powerful demon Neyn. He serves as Neyn's errand boy and is initially ordered to kidnap Fuyumi and bring her to the family estate. It is later revealed that Fuyumi is also his sister, which changes the dynamic of his mission. Knell has short blonde hair that covers one side of his eye, gray eyes, and is usually seen wearing a blue jacket and jeans. His personality is snarky and somewhat sarcastic, but beneath that he shows a considerate and caring side, particularly toward Fuyumi even while he is tasked with capturing her. His primary motivation is to follow his mother's commands, but after discovering his true relationship with Fuyumi he begins to question his allegiance and becomes more protective of his siblings. In the story, he plays a supporting role in the Hydra family arc, acting as an antagonist at first but later aligning with his brother and sister once the familial bonds are clarified. His key relationships are with Bell, Fuyumi, and his mother Neyn; through his interactions with them he develops from a simple errand boy into a more independent and affectionate brother. Information about his notable abilities is sparse, and the available sources do not detail any specific powers or combat skills he possesses.