I didn't mind Ako because there were barely any physical contact between the two unlike a certain neck-biting, smug, masochist bloodsucker who could've bitten from the arm or something
Ako is gonna seduce him for fun and then later falls in love with him. And when she tells Tsumiki this, Tsumiki will PROBABLY realize her own feelings. Now it can go either two ways. One: She realizes her feelings for Yutaka. Or two: She thought she has feeling for Ako.
The difficult part is, fantasy succubi are clearly female. So the word "суккуб" should be grammatically female too, and that's where people get creative. Diminutive "суккубка" is the most common version.