Thirteen is a human resident of Hole and a recurring minor character. He maintains friendships with Nikaido, Vaux, Haze, and Jonson, frequently visiting the Hungry Bug restaurant where Nikaido works. His physical appearance features dirty blonde hair, pointed teeth, and distinctive red stripes on each cheek. He typically sports a hat with a stripe, a spiked jacket, a t-shirt prominently displaying the number "13," tight pants, and a plaid skirt-like garment. Personality-wise, he exhibits a laid-back demeanor but reacts with extreme emotions like irritation, fear, or anger to situations. He displays cowardice when confronted with danger and initially shows romantic interest in Nikaido, though this later evolves into platonic loyalty. His background establishes him as a regular at the Hungry Bug, where his interactions include competing with Kaiman for gyoza. He joins Vaux's hospital baseball team to fill a roster spot against the Heiwa Clinic Sharks. During the game, he questions Kaiman about his relationship with Nikaido and expresses concern when Fujita aggressively pitches at her. After Kaiman departs for the sorcerers' world, Thirteen observes the increased business at the Hungry Bug. He attends Vaux's birthday party when Nikaido's identity as a magic user is revealed, reacting with confusion and fear before the group is attacked by a mushroom monster. Teleported to En's mansion, Thirteen is imprisoned and transformed into a mushroom-headed state by En's magic, leaving him incapacitated until Noi heals him. Following his recovery, he participates in a mission with Vaux, Kasukabe, and Jonson to locate Kasukabe's wife in the Hydra Forest. Disguised as goons, they travel by stolen minivan. During an ambush by Cross-Eyes gang members, Thirteen suffers a machete injury. Vaux helps him hide in a storage closet until Shin rescues the group. After returning to Hole, Thirteen expresses relief at being home and disgust at the spoiled remains of Vaux's birthday party.