Midori Nishimura, Haru Nishimura's younger sister, possesses fair skin, blue eyes, and short light brown hair typically secured by a white headband. She favors a yellow dress and light pink slip-on shoes. Injuries from a car accident two years before the main events leave her dependent on a crutch for mobility and necessitate a brace on her right leg; this same accident claimed her mother's life. Midori harbors profound guilt, convinced the accident was her fault and secretly fearing Haru and others blame her for their mother's death. She first appears observing Haru's martial arts practice with Furuichi Teraoka before reminding Haru it's time for school, departing with them. After the Northern Government attacks Sentan Island, Furuichi confirms Midori's safety to Haru. However, military forces later forcibly transform Midori into a humanform weapon. During this transformation, Haru attempts to reason with her, underscoring the emotional complexity of their relationship amidst the conflict.