Noa Rukina is the younger sister of Yuno Rukina, a prominent scientist dedicated to researching the Hadean threat and the Book of the Dead. After Yuno perishes in an early Hadean attack, Noa immerses herself in humanity's struggle for survival. She traverses a post-apocalyptic landscape alongside Shu Aiba, the transformed Necrodiver, and her close friend Iera Hamon. Noa and Iera share an intensely close bond, constantly supporting and shielding each other throughout their journey, a dynamic central to her interactions. Her scientific background occasionally shapes her view of the crisis, though specific professional roles remain undefined. Noa wears practical gear: shorts, boots, a scarf, earrings, a bag, and a belt. Her personal evolution focuses on processing grief, surviving a world besieged by hostile entities, and upholding unwavering loyalty to her allies amid rising dangers.