Marie Yamano is a supporting character in the series, first introduced as the mother of the protagonist Ban Yamano. Her background is marked by personal tragedy: her husband Junichirou Yamano died in a plane crash, and she initially blamed that loss on the existence of LBX, the battling robots that were her husband's creation and Ban's passion. This loss colors her early personality, making her cautious and protective. At the start of the story, she does not support Ban playing LBX, fearing that the hobby carries the same danger that claimed her husband. Despite her grief, she is a strong and resilient woman who raises her son on her own. Over time, her motivations shift from outright opposition to quiet acceptance; when she sees how important LBX is to Ban and how it connects him to his father's legacy, she eventually supports his decision to continue. Her role in the narrative is primarily domestic, serving as the emotional anchor and occasional moral counterweight for Ban. Her most significant relationship is with Ban, though her late husband remains a constant presence in her thoughts. Her character develops as she learns to separate the tool from the tragedy, moving from blame to understanding. She does not possess any combat or hacking abilities; she is an ordinary mother whose strength lies in her perseverance and her evolving care for her son.