I think that She said it because She was afraid of Hana's reaction, denial is common in this kind of story and She didn't want Hana to think that She was abnormal (omosexuality is an issue in this manga)
Prediction: Yuki confront Kurumi. Failed to convince her. Halfway through the talk, the melee leader dude was taking Miki as hostage and plan to run away to the company place to find a cure. Kurumi save Miki with her zombie powar. Miki successfully convince Kurumi to stay. The team heads to the drug company. Found the cure for Kurumi. Time skip. Kurumi and Miki marry in near future (because screw the government), make an awesome zombie fighting duo.
(Yuki follow Negu-nee path to become a high school teacher. While Rii becomes an elementary teacher to recover the hole Ruu left behind her. The two will hang out late after school and have their own things)
