Tsuchigomori occupies dual roles as a supernatural entity and middle school teacher at Kamome Academy, embodying the identity of School Mystery No. 5: Curator of the 4PM Bookstacks. This position grants dominion over a library housing color-coded records of students’ lives—white for the living, black for the deceased, and red for forbidden texts that draw supernatural hostility. Though capable of reshaping futures through these archives, he refrains, a choice that carries the peril of his own erasure. His human guise presents a tall, lanky frame with spiky black hair streaked by white, purple eyes behind golden glasses, and a purple sweater. This facade masks his true form: sharp ears, clawed hands, shark-like teeth, and six limbs—four spider-like arms coiled at his lower back. In 1969, his appearance diverged, sporting entirely black hair, no glasses, and a dress shirt. Beneath a veneer of meek mentorship lies a sharp-tongued, mischievous entity prone to sarcasm and sadistic theatrics, often intimidating students like Nene Yashiro and Kou Minamoto. He relents only when cautioned by Hanako, though latent care surfaces through guidance and emotional support, particularly for Nene after disclosing his ties to Hanako’s history. His past centers on Hanako, once Amane Yugi—a student in 1969 whose tragic fate Tsuchigomori foresaw. Attempting to steer Amane from his destined end, the teacher watched in shock as the boy defied fate by transforming his yorishiro into a lunar rock—a gift from Amane himself. The student’s premature death left Tsuchigomori grappling with regret, murmuring, “He wasn’t supposed to die that early.” Relationships weave complexity: a subordinate yet protective dynamic with Hanako, marred by lingering guilt; contentious exchanges with Yako (School Mystery No. 2) that hint at mutual respect beneath insults; and reluctant tolerance of Kou’s antics, permitting library access despite irritation at the nickname “Spider-face.” Spin-offs expand his role into comedic chaos—dragged into a supernatural Game of Kings with no escape under Hanako’s rules, or weathering a candy-driven Mokke uprising sparked by his unintended inspiration. These scenarios highlight dry wit and unexpected patience, contrasting his stern authority. Trivia notes shivers through cold weather, avoidance of car travel, and a sweet tooth for bekko candy. His dual identity strains his routine, while his name—a twist on the yōkai Tsuchigumo, modified with “go” for his mystery number—echoes his mythic origins.