Issa Mihotoke, known to most as Buccha, is a prominent character who begins his journey as an antagonist before becoming a core member of the Kogarasumaru team. Buccha is a heavily-built, tanned youth with a bald head and a characteristic set of three lines on his forehead, a design that pays homage to the wrestler Abdullah the Butcher. He typically appears with a large, rotund frame, giving the impression of being obese, but this is deceptive; his body is actually only ten percent fat.

Buccha’s background reveals that he was originally the leader of the team Night Kings, also known as Yaou, through which he dominated Higachu Junior High School. His path changes after he loses a Parts War, a high-stakes Air Treck battle, against the protagonist Ikki. Following this defeat, he abandons his villainous ways to become a stalwart ally and a founding member of Kogarasumaru. His family life includes his father, who is a Buddhist monk, and it is mentioned that he is dating the sister of a character named Mr. Orihaya.

In terms of personality, Buccha presents a dual nature. In his daily life, he is an amicable and friendly person who enjoys relaxing and has a great love for food. However, when the subject turns to battle, a more serious and devastating side of him emerges, turning him into a formidable killing machine focused on close-quarters combat. His core motivation is tied to his role within Kogarasumaru, where he serves as a powerhouse and a reliable support for Ikki. He is characterized as a Power-type rider and is often compared to a tank for his ability to deliver and withstand massive amounts of damage.

Buccha's role in the story is that of a powerful fighter whose strength is essential to the team. He is often called upon to handle opponents that require raw, overwhelming force. His key relationships are central to his character arc. His most important bond is with Ikki, whom he respects as a leader after his defeat. He also has a close friendship with his teammates, including Kazu and Agito, frequently fighting alongside them. His father also plays a crucial role, providing him with mental and spiritual training to overcome his shortcomings.

The character undergoes significant development, primarily concerning his mental fortitude. Although he possesses the potential to rival a King, one of the top-tier riders, he initially lacks the mental will and confidence to fully utilize his abilities in battle. To remedy this, he undergoes rigorous mental training with his father, a Buddhist monk, which helps him achieve a calmer, more focused, and "zen" state during fights. This allows him to gain better control over his emotions and unlock new levels of power.

Notable abilities stem from a unique physiological quirk: his large size is caused by a surplus of blood pooling in his abdomen from overeating. His signature technique, Bump Up, allows him to redistribute this blood to his muscles. This transforms his body, revealing a much leaner, incredibly muscular physique with enhanced strength and reach. In this state, his power is so great that his rider "shadow" manifests as a tank. He rides on a customized pair of Air Trecks that resemble miniature jeeps and uses studded gloves to maximize his destructive power in close combat. As he progresses, he masters variations like Bump Up Reversal, which sends blood to his lower body to create Buccha High-Speed Light Tank Mode, granting him tremendous speed to complement his power. He eventually reveals his mastery over his own unique path, known as the Rock Road. His body also contains over ten times the normal amount of blood, storing enough oxygen in his hemoglobin to allow him to hold his breath for over twenty minutes, enabling him to fight effectively underwater.