TV-Series
Description
Kotaro Nomura is a student at Hazakura Academy and a classmate of Hiro Amanokawa, residing in room B-08 of the Hazakura Boys' Dormitory.

On October 8th of his first year, Kotaro approached Hiro to borrow his homework, receiving advice against copying it directly. He then shared rumors of a female student falling victim to the "Sewn-lip Man" the previous day. Later, when Hiro questioned Kiyoshiro Higashimitarai about his bandages, Kotaro interjected to ask if the Sewn-lip Man was responsible, a question that visibly frightened Kiyoshiro.

When a teacher tasked both boys with carrying boxes to a storage area, Kotaro showed little enthusiasm for the chore and commented on Hiro's readiness to accept requests from others. Their path led them to the school auditorium, the site of the recent attack, where Kotaro showed Hiro a post on the Lirurun social media account seeking information on the Sewn-lip Man. Eager to get a picture, Kotaro convinced Hiro to pick the lock so they could enter the building and wait for the creature to appear.

Inside, when Clockmon appeared, Kotaro excitedly snapped multiple photographs. This action provoked Clockmon to attack him and steal his time, causing Kotaro to rapidly age into an old man. The teacher Aida-sensei and the Math Teacher arrived at the auditorium before Clockmon could attack Hiro; they discovered the aged Kotaro, and he was subsequently hospitalized.

After Gammamon defeated Clockmon, the effects of the time theft were reversed and Kotaro returned to his normal age. During his hospital stay, however, his mother discovered he had been flirting with a nurse and forced him to leave. Kotaro returned to the dormitory on October 10th. There, he noticed Gammamon but accepted Hiro's explanation that it was an AI-generated hologram. He also observed Kiyoshiro behaving in a strangely scared manner.

In a later incident, Kotaro played an online fighting game and subsequently disappeared. It was discovered the Digimon Kinkakumon and Ginkakumon were responsible for kidnapping players who lost the game, trapping them inside a gourd to be transformed into sake. Hiro and his friends intervened, leading to Kotaro's rescue.