Thinking that somehow Kou is going to attempt or be tempted to drink that girls blood but gets stopped by Nazuna. That would show that he has become part vampire, but it may also end up pushing them farther away from each other.
Oh, not this bullshit "Instead of discussing situation on hand let's just disappear form their life and leave them in the dark". We don't need forced drama when there is already have pretty serious conflict in play.
Cats should be with other cats its only natural. I've always thought kou and Nazuna had a Haruko and Naota vibe but now miss detective is reminding me of Amurao