Raishin Akabane is the main protagonist of the Unbreakable Machine-Doll series. He is a teenage boy of Japanese origin with brown hair cut to ear length and blue eyes, and he belongs to the Akabane clan, a prestigious family known for its mastery of puppetry. He is the elder son of Kuukan and Yoshino Akabane, the younger brother of Tenzen Akabane, and the older brother of Nadeshiko Akabane. He is also the last known survivor of his clan after most of its members were killed in a massacre. Raishin comes to Britain as a transfer student at Walpurgis Royal Academy of Machinart in Liverpool, accompanied by Yaya, a girl-shaped automaton created by the celebrated dollmaker who also made the three sister dolls of the Snow Moon Flower series. His public goal is to win the Night Party, the academy's tournament that decides who receives the title of Wiseman, the highest honor a puppeteer can achieve. His true purpose, however, is to get revenge against his older brother Tenzen, a genius whom he holds responsible for the destruction of their family. In addition, he acts as an undercover agent for the Japanese military, a role he himself describes in blunt terms as being the military's dog, though he is determined not to let that assignment compromise his personal mission.

In personality, Raishin is audacious, decisive, and outspoken. He tends to make choices quickly and is just as quick to refuse offers he does not want. He often presents a relaxed and playful manner, joking and bantering with the people around him, which sometimes irritates his allies. Beneath that casual surface lies a serious and fiercely determined young man who remains calm under pressure and refuses to back down, even against opponents with far more experience or status. He has a strong sense of duty and is particularly driven to protect others, especially women in need, a tendency that comes from regrets in his past. He is loyal and protective toward those who earn his trust, and although he can be sensitive when misunderstood, his concern for others tends to show through his actions rather than his words.

His motivations combine revenge with ambition. He enters the academy hoping to improve his skills and become the best puppeteer in the world, but the real force behind his participation in the Night Party is the desire to confront his brother Tenzen. Over the course of the story, he becomes caught up in larger conflicts involving powerful magical automatons known as divine machine-dolls, as well as the political tensions that point toward a coming world war. Despite his grim objective, he repeatedly puts himself in danger for classmates and allies, and he gradually moves from being a lone avenger to becoming a dependable figure within the school.

In the story, Raishin functions as the central character around whom the conflicts of the academy revolve. He begins as an overlooked newcomer who is mocked for his poor examination results, which earn him the ironic nickname Raishin the Apprentice and a reputation as one of the lowest-ranked students in his year. Yet his combat ability quickly sets him apart, and through decisive victories and a willingness to fight for others, he earns respect and gathers allies. His early path includes challenging Charlotte Belew, one of the leading candidates for the Wiseman title, to a duel in order to take her place in the Night Party, a confrontation that eventually develops into a meaningful bond.

His key relationships shape much of his development. Yaya, his automaton and closest companion, is the most important figure in his life. Their relationship is marked by playful teasing and casual conversation, but beneath that banter is a deep bond of trust and devotion; she fights fiercely for him, and he cares for her genuinely, relying on her completely in battle. The dollmaker who gave him Yaya also holds influence over his actions, as he carries out the mission she assigned him at the academy. His relationship with Charlotte grows from rivalry into alliance and friendship, and her circle, including her brother Loki, becomes an important part of his life at the school. At the heart of his story is his bond with his brother Tenzen, believed to be the academy's top student known as Magnus. Once family, the two are now locked in a conflict driven by Raishin's desire for vengeance, and this relationship gives his journey its emotional weight.

Raishin develops notably over the course of the narrative. He starts as an isolated student carrying hatred and a single-minded goal, but his experiences with Yaya and his growing number of allies gradually broaden his perspective. He learns to fight for the people around him as well as against the enemy who destroyed his family, and he matures from a reckless underdog into a more composed and strategic fighter. Even as he gains discipline and responsibility, he never loses the defiant and straightforward spirit that defines him.

His notable abilities lie in combat rather than academics. Although his test scores are poor, his battle instincts and physical prowess far exceed those of his peers. He is one of the few puppeteers who can fight effectively even without his automaton, combining hand-to-hand martial arts with magic in a distinctive fighting style. As a puppeteer, he commands Yaya with precision, using her speed and power to overwhelm opponents, while his own sharp reflexes allow him to handle threats directly. He also makes use of a weakened version of a secret technique of the Akabane clan, a traditional art that is among the most powerful abilities available to him. His quick decision-making, adaptability, and ability to read opponents allow him to overcome rivals who are more experienced, better ranked, or more formally talented than he is.