Maihime Tenkawa, known to most by her affectionate title of Princess, is the chief of the Kanagawa city and has held the position of the strongest individual in her region for an uninterrupted span of ten years. Physically, she is a young girl of notably short stature, standing at 145 centimeters, with silver hair typically styled in twin tails and red eyes. Despite her small frame, her presence is commanding, often accentuated by her military-style attire.

Her personality is defined by an overwhelming and unshakeable optimism. Maihime is a pure idealist who operates almost entirely on instinct and impulse rather than careful deliberation. She is straightforward, energetic, and can be simple-minded, charging headfirst into situations with a boisterous and cheerful demeanor. This childlike exuberance, however, is paired with the confidence and authority of a long-reigning leader. While she is kind and strives to get along with her peers, her straightforward nature can sometimes clash with the more complex personalities of leaders from other cities. Her philosophy in combat is one of overwhelming force, a self-proclaimed big gun主义 (big gun-ism) where the best solution is to obliterate the enemy with a single, massive strike from her enormous sword.

Beneath her carefree exterior lies a deep loyalty to her friends and allies, which serves as her primary motivation. She treasures her companions and never acts arrogantly despite her immense power, a quality that has earned her the genuine love and admiration of all students in Kanagawa. This fierce protectiveness is most evident in her relationship with her closest companion, Hotaru Rindou, who serves as her second-in-command and subordinate. Maihime and Hotaru were childhood friends, and together they underwent the cold sleep process, making a promise to one day meet again. This bond is the cornerstone of Maihime's world; she harbors an extreme level of trust and dependence on Hotaru, stating plainly that she likes her. This commitment is so absolute that even when she learns Hotaru has been assigned to assassinate her, Maihime refuses to fight back, determined to find any other way to keep her by her side.

Maihime's role in the story is that of the strongest asset for humanity in their war against the Unknown. She is a frontline combatant whose primary function is to act as a devastating powerhouse in battle, capable of single-handedly destroying waves of enemies and boosting the morale of her allies. Her fighting style relies not on technical skill but on a suite of supernatural instincts, including rapid reaction times, incredible dynamic vision, and the ability to sense killing intent and predict enemy movements, all of which she claims come from gut feeling rather than thought. Her primary weapon is a massive sword forged from 100% pure命铁 (Meitetsu, or destiny steel), which is longer than she is tall.

Her ability, known as a World, ranks first in terms of pure destructive power, exceeding common sense. However, this power is not always perfectly controlled, sometimes leading to collateral damage. Over the course of the narrative, Maihime undergoes significant development. Initially a symbol of unquestioning strength, she is forced to confront painful truths. She eventually uncovers the hidden reality of the world she lives in. Upon discovering this truth, she makes the conscious choice to abandon her role as a defender of the established order and instead aligns herself with the human阵营 (camp), leaving with Hotaru Rindou to forge a new path based on the truth they have uncovered.