Description

He is a science teacher at Kamome Academy. He keeps it a secret that he is actually a ghost, representing School Mystery No. 5, the 4 p.m. bookshelves. Additionally, he is Kou's homeroom teacher. He is a tall and lanky man. He has spiky black hair with long white bangs and purple eyes. When disguised as a human, he appears almost indistinguishable from any normal person. In his true supernatural form, he has noticeably sharper features, such as pointed ears, claw-shaped hands, and shark-like teeth; he also has four additional limbs protruding from his lower back. He wears a white coat with a purple sweater underneath and gold glasses.
In 1969, he is shown to have completely black hair and does not wear glasses. His sweater is also replaced by a dress shirt.

Tsuchigomori seems like a normal, caring, and somewhat docile teacher with his human disguise. In reality, he's sarcastic, mischievous, and rather quick-tempered. He has also been shown to be quite sadistic, enjoying threatening and scaring Nene and Kou, although he quickly stops after a slight warning from Hanako. Although he is a teacher, he is shown to dislike children due to their noisy attitudes. Tsuchigomori also has a strange sense of humor and likes to joke, such as saying he enjoys eating human children, only to be met with terrified looks in response.

Although he claims to only pretend to care about his students, it has been shown that he truly cares for them on several occasions. When asked why he makes his teacher persona so different from his true supernatural personality, he responds that it is simply because he feels like it.
As the curator of The Bookshelves at 4:00, he has access to all the knowledge surrounding the school, along with the present, past, and future. He seems to know everything about all the students who have attended the school. Even after his Yorishiro and limit were broken, his powers still allow him ways to retrieve books from the library. He mentions that due to his position, it is possible for him to alter the future, but he does not plan to do so because any curator who does will be erased from existence.