Movie
Description
Hayato Shinkai is a prominent third-year student at Hakone Academy and serves as the team's ace sprinter, wearing the number four bib. He is a tall young man with an athletic build, orange hair, and blue eyes, often seen with a calm and somewhat detached expression.

Shinkai's background is defined by a traumatic incident that occurred during a race in his second year. In his eagerness to win, he passed another rider illegally on the left and accidentally ran over a mother rabbit, killing it. He found the rabbit's orphaned baby on his way home and, deeply wracked with guilt over taking a life for the sake of victory, he took the baby rabbit, named Usakichi, to raise at Hakone Academy. This event created a severe psychological block: Shinkai became unable to pass any other cyclist on their left side, instinctively braking for fear of something jumping into the road. The guilt was so overwhelming that he rejected his position in that year's Inter High, much to the disbelief and frustration of his teammates, particularly the captain, Juichi Fukutomi.

Despite his calm and caring nature, Shinkai possesses a fierce competitive spirit. He is generally laid-back, quiet, and does not seek the spotlight, but he is a serious and formidable competitor when racing. He is also known to enjoy food, often carrying power bars with him. This placid exterior hides an intense drive, which earned him the old nickname the straight-line demon before his accident. In crucial moments, this side of him resurfaces as a wild, frenzied, and almost manic persona he unleashes when he is fully committed to winning, living up to the demon part of his title.

Shinkai's primary motivation is to live up to the expectations of his team, which supported him in his recovery. After the accident, his captain, Fukutomi, made him promise to race in the next year's Inter High, reserving the number four bib for him as they aimed to build the strongest team. With the help of his teammates, including Yasutomo Arakita, who practiced with him to become expert at passing on the right, and Jinpachi Toudou, Shinkai worked to overcome his trauma, though he still harbored the fear going into his final Inter High.

In the story, Shinkai plays a crucial role on Hakone Academy's team as their ace sprinter. During the second day of the 41st Summer Inter High, he confronts the Kyoto Fushimi team's ace, Akira Midousuji, at a sprint checkpoint. Midousuji, having heard the rumor of Shinkai's trauma, intentionally leaves space on his left, taunting him and daring him to pass. Cornered and remembering the support of his friends, Shinkai finally breaks through his psychological block. He unleashes his old demon persona and engages in a fierce sprint battle with Midousuji. Though he loses the checkpoint by a razor-thin margin, the act of overcoming his fear is a significant personal victory. On the same day, he later repays Fukutomi's faith by launching him forward at a critical moment, directly contributing to Fukutomi's victory on the second day and helping the team regroup.

Hayato Shinkai shares a deeply significant bond with his captain, Juichi Fukutomi. They have been friends since middle school, where they served as captain and vice-captain. Fukutomi was one of the few people who could not hide his distress when Shinkai withdrew from the Inter High, but he came to understand his friend's trauma and made him promise to race the following year. Fukutomi holds immense trust in Shinkai, believing in his strength because he has persevered through low points. The two have a near-telepathic understanding, with Shinkai often able to interpret and elaborate on Fukutomi's stoic, unspoken thoughts. He also has close relationships with Arakita, who helped him train, and Toudou, showing a more relaxed and even teasing side with them outside of competition.

Shinkai's most notable ability is his explosive sprinting power, particularly on flat terrain. His signature technique is a drastic personality shift mid-race. He transforms from his cool, collected self into a frenzied demon, a state that amplifies his speed and aggressive racing to terrifying levels. While this demon mode represents his greatest strength, his earlier weakness was a psychological block preventing left-side passes, a flaw directly tied to his past trauma that he ultimately overcomes through the support of his team.