Maori Hosoi is the operator of Ikoma Squad, a B-rank unit in Border. She has light skin, short spiky dark hair, and large eyes, and her Trion Body wears the standard operator uniform without a tie. Hailing from Hyōgo, she was scouted by Border and assigned as the squad’s operator. Raised with older brothers who set very high expectations, Hosoi grew up rarely receiving praise, which left her unaccustomed to compliments. When her teammates do compliment her, she becomes flustered and often demands they stop or even stops the behavior that earned the praise. She comes across as high-strung and somewhat standoffish, a contrast to the easygoing, nonchalant attitudes of her squadmates—Tatsuhito Ikoma, Satoshi Mizukami, Kai Minamisawa, and Koji Oki. Their laid-back behavior regularly frustrates her, especially Ikoma’s tendency to share lengthy, pointless anecdotes instead of strategizing before rank wars. Despite this friction, she is deeply dedicated to her role. She excels at multi-tasking and processing information, efficiently monitoring all four combatants during matches and issuing timely warnings about approaching enemies or sniper positions, even in complex four-way battles. Her performance remains steady despite the high workload. She speaks in a Kansai dialect, like most of her teammates except Minamisawa. Her hobbies include writing novels, making plush toys, and composing songs, but she rarely shows the results to others. She likes inari sushi, dandan noodles, flowers, and cute things. Her nickname is Mario, a reference likely inspired by a video game character. Her relationships with her teammates are marked by a mix of exasperation and genuine care: she addresses Minamisawa by his first name without honorifics and scolds him for charging in alone, while Mizukami appears attracted to her, Oki enjoys teasing her, and Ikoma’s belated, repeated compliments embarrass her. She has shown jealousy when Ikoma called another girl cute. Over the course of the story, Hosoi remains a competent and committed operator, though her discomfort with praise and her squad’s carefree nature continue to define her interactions.