Otoya Todoroki is a main character in the anime You Don't Know Gunma Yet: Reiwa Version. He is a teenage student who originally lived in Chiba Prefecture before his family relocated to Gunma Prefecture during his elementary school years. His move is the reason his former friend, Nori Kamitsuki, later transfers to a school in Gunma in order to follow him. As Nori makes the journey, Todoroki sends him an ominous text message telling him to turn back and warning that once a person enters Gunma, they never return. The message reflects his firsthand awareness of the prefecture's strict and intimidating local culture, and it establishes him as a character who understands how overwhelming the experience of relocating to Gunma can be for an outsider.

Physically, Todoroki is a male teenager with shoulder-length reddish hair, described in some sources as aubergine-colored, and dark eyes. He is also identified as a member of a student group known as JKJ.

His role in the story centers on his connection to the protagonist, Nori Kamitsuki. The two were friends in Chiba before Todoroki's family moved away, and their friendship provides the narrative link between Nori's former life and his new surroundings. Todoroki's personality comes through mainly in his cautious and protective attitude toward his friend: despite living in Gunma himself, he tries to keep Nori from coming, suggesting both genuine concern and a realistic understanding of the difficulties Nori will face. As a character who has already adapted to Gunma's ways, he represents the perspective of someone familiar with the region's demanding customs, serving as a point of reference for the protagonist's own adjustment.