Tsurumi is a short man in his old age with gray hair, round eyeglasses, and thick eyebrows and mustache. He also wears a black skull cap. His guardian uniform consists of a black tuxedo, over a white dress shirt, with a red tie, and black pants.
According to Kotarou, he is a man with a mysterious aura around him. He always sits it the background and doesn't seem to communicate with others, much like Haruhiko Yoshino.
He first appears with the rest of the Knights in the forest where they save Kotarou from being killed by a dinosaur-familiar.
He attends Lucia's going away party but doesn't speak for the entire evening.
- Chainsaw: He is said to use a chainsaw in battle.
- He is able to produce traps using his chainsaw.