Mamiina is a sixteen-year-old Sibylla from the advanced nation of Simulacrum. She grew up in poverty because of her parents' debt, which led many others to look down on her. To get by, she and her parents served the household of Rodoreamon, a wealthy and influential family. Despite her humble origins, she rose to the rank of Sibylla by volunteering for combat duty when others refused. She possesses considerable piloting skill and is known for her haughty, cold, and harsh demeanor, especially when she first joins Chor Tempest. Her primary motivation upon transferring to the unit is to become the partner of Neviril, believing that pairing with a famous Sibylla would bring her acceptance and legitimacy. This ambition goes unfulfilled, however, as Neviril chooses Aaeru instead. Over time, Mamiina's abrasive exterior softens, and she grows into a more helpful and endearing member of the team. She develops a close bond with her fellow Sibylla Yun, who enters Chor Tempest at the same time under similar circumstances, and her relationship with Rodoreamon evolves beyond that of servant and master. Her death in battle becomes a pivotal moment for the group, deepening the grief and sense of loss that drives the later episodes. In addition to her combat abilities, Mamiina enjoys cooking and cleaning, finding comfort in domestic tasks.