Shinichirō Yamamoto is a first-year Mechanical Engineering student at Izu University with a chubby physique and short red-brown hair parted in the middle. He typically wears plain t-shirts under sweatshirts paired with sweatpants.

Yamamoto exhibits a strong preoccupation with securing a romantic relationship, frequently voicing his desire to find a girlfriend. This fixation stems from his virginity, which causes him significant personal concern. His resentment toward classmate Yū Mitarai arises from Mitarai's success in maintaining a girlfriend, creating tension between them. Yamamoto perceives Mitarai's relationship as a constant reminder of his own unmet romantic aspirations.