Axel serves as the caporegime, or a high-ranking member, of the Oz family. His character is deeply rooted in his origin as the Tin Man from The Wizard of Oz, having been transformed into a human after receiving a heart from the wizard. This backstory is central to understanding his personality and struggles, as he possesses a heart but has not yet learned how to fully understand or express the emotions it provides.

In terms of personality, Axel is famously taciturn and blunt, often coming across as unapproachable or intimidating due to his silence and harsh manner of speaking. He generally prefers to follow orders rather than act on his own initiative and tends to keep to himself, often confining himself to his room. Despite his cool and gruff exterior, Axel has a notable fondness for sweets, a hidden soft spot that contrasts with his stern demeanor. He is also deeply protective of his boss, Caramia, and his loyalty to the Oz family is one of his defining traits.

Axel's primary motivation throughout the story involves learning to navigate his newfound capacity for emotion. He is an honest and dutiful individual, but he struggles with understanding his own feelings and the feelings of others, which often leads to awkwardness and misunderstandings. His role in the story typically begins with him acting as a reluctant guardian to the protagonist, Fuka, following orders from Caramia to watch over her. He is initially suspicious of her claims of memory loss, treating her with distance and formality. However, his attitude shifts after she demonstrates her sincerity and courage, such as when she attempts to rescue him from the rival Wolfgang family, an act that proves her trustworthiness.

Key relationships shape much of Axel's development. His dynamic with Caramia is one of unwavering loyalty and protectiveness, though he often defers to his boss's authority. His relationship with Kyrie, the family's consigliere, is more complex; Kyrie frequently teases and bullies Axel, commenting on his poor aim or lack of social grace, yet this is presented as a form of twisted camaraderie rather than genuine malice. The most significant relationship is with Fuka. As the story progresses, Axel begins to open up to her, revealing his insecurities, such as his poor marksmanship and his fear of hurting her with his own strength. This romance forces him to confront his emotional inexperience directly, as he is unsure how to act as a boyfriend and worries that Caramia might be a better match for her.

Axel's development is marked by his journey to understand and use the heart he was given. Initially emotionally robotic and detached, he gradually learns to identify his feelings of affection and protectiveness. His arc often involves him regaining or learning to fully utilize his "heart," which is portrayed as a precious yet fragile treasure that can be lost or damaged. This personal growth is tied to his courage to accept his own emotions and to trust in his relationship with Fuka, moving from a state of following orders to acting on his own heartfelt desires.

Notable abilities include his incredible physical resilience. He possesses an abnormal healing power, which Kyrie often exploits by using him as a shield or cannon fodder in dangerous fights, knowing he can recover. While he carries a shotgun, his aim is famously terrible, to the point where he is more likely to use the gun as a blunt instrument, swinging it like a club or an axe. This fighting style is a direct remnant of his time as the Tin Man, as his preferred weapon is actually an axe. However, Kyrie forbids him from carrying an axe, finding it inappropriate for a modern mafioso, so he is forced to use a firearm he cannot effectively shoot.