@Fri
The reason the MC hasn't turned into a vampire yet isn't that Nazuna is being stubborn in any way. He needs to be in love with Nazuna before he can turn into vampire. Until then, she can't turn him into one.
Usually, in hentai, the childhood friend would be like " I don't want you to sleep with Aya, so fuck me instead. That way I can protect Aya."
Considering the kind of person Sei is, she probably wouldn't mind.
@snorkofob Yep. I wasn't satisfied with the conclusion of this fight because Chidori took the blame for the whole thing. Additionally, Nanoha not owning up to her own stubbornness kinda irks me.