Kazuya Aoshima, often called Kazu by his friends, is a main character who is the same age as Ban Yamano and Ami Kawamura, attending the same school though a different class. His background reveals that he has been a close friend of Ban and Ami since childhood, and he possesses a deep knowledge of LBX mechanics, particularly regarding the internal chips of the machines. In the earlier parts of the series, Kazuya comes across as somewhat rough around the edges, but he is fundamentally a good-natured person who shows courage when his friends are in danger. Initially, he displays a lack of confidence and a tendency to give up quickly when faced with difficult situations, yet he consistently acts harshly towards anyone who seeks to harm his companions, a trait that initially puts him at odds with Jin Kaidou before he accepts Jin as a trusted comrade. His motivations are largely driven by loyalty to his friends and a desire to protect them, which evolves over time from reluctance to actively stepping forward in battle. In the story of Danbōru Senki W, Kazuya goes missing after being captured by the organization Detector, during which time his LBX Fenrir is severely damaged. When he reappears in episode 29, he has undergone a dramatic transformation, both physically becoming more muscular and mentally becoming more confident and powerful as a fighter. While initially appearing as a brainwashed slave player, it is revealed that he faked this status; an accident caused his control collar to loosen, allowing him to break free from the brainwashing and learn the truth about Detector, after which he chose to cooperate with the masked man to help Ban fight the true enemy. His key relationships include his childhood bond with Ban and Ami, as well as a later dynamic with Jin, whom he learns to trust. He also shares a notable rivalry or camaraderie with Asuka Kojo, engaging in a curry eating contest with her. In terms of notable abilities, Kazuya is a top-notch LBX player who specializes in sniping and artillery fire, utilizing cool judgment and keen observation to grasp his surroundings during battle. He demonstrates skills such as using a tracker with a magnetic bomb to stun enemies and unlocking stinger missiles for his LBX Hunter. His primary LBX units include Warrior, Hunter, Fenrir, and later Achilles Deed.