|Age||13 - 14|
|Family||Nyen, Hydra Bell, Heads Hydra, Yanagi Fuyumi|
|Debut: Anime||Episode 7|
|Voice Actor||Japanese: Yuuki Kaji
English: Erik Scott Kimerer
Hydra Knell is Bell's and Fuyumi's younger brother and Nyen's errand boy/son.
Knell has short blonde hair that covered one side of his eye, blue jacket and jeans.
Despite his snarky side, Knell is shown to be considerate towards others, even Fuyumi who he is suppose to be kidnapping her as he offer her meals. While annoyed at his sister for kicking him at the crotch, Knell worries about her when her feelings for Staz didn't reach and went depress, even feeling bad for egging her on.
- Spatial Magic: Spatial Magic is the ability to travel through gaps in space in order to reach a different destination. The Hydra is able to transport to anywhere just by willing it, while Knell requires a blanket to jump through. By opening a frame or space, one is also able to see through it, like a window, allowing for someone to be spied on. Knell is shown to be a very skilled at Spatial Magic, though his abilities aren't as advanced as Bell's.
- Blanket: Knell is able to use his spatial magic whenever there is a blanket.
Sister: Hydra Bell
Father: Heads Hydra