Eruna is a somewhat dimwitted girl who has a romantic interest in girls and as a result spends much of her time playing dating simulation visual novels on her portable device. She enrolls into Mikagura Private Academy after her cousin Shigure recommends it to her, largely due to wanting to be able to meet Seisa whom she developed a strong interest in. Her abilities are "Toy Gun", which allows her to shoot a powerful laser from her fingertips, and "Toy Bayonet", a bayonet made out of light, in addition to possessing incredible speed.