Yasuna Kamiizumi (神泉 やす菜, Kamiizumi Yasuna) is a student at Kashima high school and has been Hazumu's classmate since their first year of high school. Ever since she was born, Yasuna has had a unique affliction which makes her incapable of seeing males, and instead to her males are covered in a gray, hazy blur, which makes it extremely difficult for her to tell one male apart from another except through the sound of their voice. Due to this, she was never able to get along well with others; on top of not being able to see the boys in her class at school, the girls who would normally interact with them were different compared to Yasuna, which built up a divide between her and everyone else. She ended up staying alone for years, and she thought she did not mind it; she did not intend to befriend anyone anyway. However, when she stumbled across Hazumu one day in her first year of high school, she was shocked to find that she could see most of him clearly, though his face was still a blur. From that point on, Yasuna wanted to learn more about Hazumu and gradually fell in love with him. However, even when Hazumu confessed his love to her in their second year of high school, she rejected him since he was still a boy, and she was afraid that he too would one day disappear from her vision. After Hazumu's transformation into a girl, Yasuna wastes no time trying to rectify her mistake and confesses her love to Hazumu finally, but Hazumu is very confused by this and does not know what to do, especially since her physical change.
She has been practicing the flute for many years and is very good at it, so naturally she joins her school's music ensemble when she enters high school. While initially cold and distant from others, Yasuna gradually changes and becomes much easier to approach. Her friends in the musical ensemble tell her this, and ask her if she changed due to someone she likes, and Yasuna affirms this. Yasuna has shown herself to be very devoted to Hazumu, and in a conversation to Tomari, Yasuna tells her that she wants Hazumu all to herself.