Sōhei Sasahara, widely known as Sasayan, is a second-year student at Syoyo High School and a dedicated member of the baseball team. He has dark brown messy hair, dark green eyes, and stands 164 cm (5'5") tall. He typically wears his school jacket unbuttoned and is often seen in a baseball cap. Sasahara radiates a cheerful, outgoing personality and encourages others to call him by his nickname, "Sasayan." Renowned for his gentle and kind nature, he is well-liked throughout the school. His closest friendships are with Haru Yoshida, Shizuku Mizutani, and Asako Natsume. He occasionally displays cat-like expressions but can shift to seriousness when needed. His kindness manifests in prioritizing others' happiness, notably supporting Natsume's romantic interests despite his own feelings for her. He attended the same middle school as Haru Yoshida, where he also played baseball. During that time, he briefly dated a girl named Yamase after rumors of her liking him surfaced, but she ended the relationship shortly after. A significant incident involved Shinjō, whom Sasahara disliked; Haru intervened to help Shinjō while Sasahara watched helplessly from a distance. This event instilled in Sasahara a sense of debt to Haru, motivating his efforts to prevent Haru from abandoning school again. Within the main storyline, Sasahara frequently mediates group activities to maintain harmony among his friends. He develops unrequited feelings for Natsume but suppresses them upon realizing her affection for Mitsuyoshi Misawa. After Natsume is rejected by Mitsuyoshi, Sasahara comforts her by holding her hand and reassuring her of their friendship. Natsume misinterprets this as romantic interest and preemptively rejects him, causing a temporary rift. Sasahara confronts her about this assumption, leading to mutual misunderstandings: Natsume believes he pities her, while he feels she views him as an "enemy." They reconcile when Natsume acknowledges her mistake and expresses gratitude for his genuine support, admitting no other boy treated her with such honesty. Sasahara then openly confesses his feelings, though Natsume remains hesitant to pursue a relationship. Their dynamic becomes awkward, but Sasahara encourages her to act naturally. During graduation, Sasahara finds Natsume crying alone about their futures. He reassures her they can remain friends and promises to visit, noting their universities are nearby. A later photograph on Natsume's desk shows her hugging someone with Sasahara's hairstyle, suggesting a potential romantic development post-high school, though their couple status remains unconfirmed. His relationships include a warm friendship with Shizuku, who trusts him enough to gift Valentine's chocolates and discuss him with her mother. He initially approached her out of curiosity about her ability to get Haru to attend school. With Haru, Sasahara shares a bond rooted in their middle school history; he actively advises Haru on relationships and supports his connection with Shizuku, driven by his sense of obligation. Additional details note his blood type as A, horoscope as Libra, that he named Haru's rooster "Nagoya," and that he humorously requested adding "more chest hair" to an unspecified subject.