Series by 小川麻衣子

Koa Hirose, a high school freshman in Matsuyoko City, is a healthy boy with a hospitalized twin brother, Nagi. On his first day at Seisho High, Koa is chased by a masked second-year student, Nozomi Ohtori, who claims she came to take his life. Nozomi reveals she’s an alien from the planet Olberio, intent on invading Earth, and that she once saved Koa’s life by giving him her heart. Koa, grappling with this bizarre encounter, agrees to assist Nozomi in her mission, altering his daily routine. As their partnership begins, Koa navigates school life and Nozomi’s unpredictable nature, unaware of the deeper ties binding them.