Naoya Teshigawara is a student of Class 3-3 at Yomiyama North Middle School in 1998. He has light brown hair, sometimes depicted as orange, and light brown eyes, and he typically wears a blue sweater over a white T-shirt rather than the standard school uniform. In the series, he serves as the class mood maker, often providing moments of comic relief through his easy-going, carefree, and superficially lighthearted demeanor. Despite this, he shows a genuine sympathetic side and is quick to think and act when others are in danger. He was the first classmate to approach Kouichi Sakakibara after the transfer student arrived, making an effort to help him feel welcomed. Teshigawara is known among his peers by the nickname Tetsy, a shortened form of his long surname. He harbors a crush on Izumi Akazawa, though she treats him coolly, and he occasionally laments her impending move to Tokyo. Academically, he claims not to understand how he reached the ninth grade, indicating a lack of interest in schoolwork. His role in the unfolding curse of Class 3-3 evolves over the story. Initially acting as a source of levity, Teshigawara becomes increasingly serious as the mysterious deaths escalate, and he participates in the group's efforts to investigate and stop the calamity. He is a devoted friend to Kouichi, Tomohiko Kazami, and Yuya Mochizuki, and his loyalty leads him to act impulsively to protect them. In a critical sequence, he attempts to save Yuya from a dangerous situation, but Tomohiko misunderstands his actions and confronts him; panicked, Teshigawara flees and is electrocuted, becoming another victim of the curse before the calamity is resolved. His primary abilities lie in his athleticism, his quick thinking under pressure, and his natural optimism, which helps to counterbalance the increasingly grim atmosphere among the group.