I would venture to say that adventure is far more integral to the RPG experience
Only in an adventure-oriented RPG. Which, granted, is exactly what this is.
But, you know, you could have a War RPG or any number of other RPG variations that don't involve adventuring.
And for a lot of people, the Adventure genre (both in film and games) involves romance in some form.
Define "RPG elements".
I'm pretty sure "role-playing" could be an essential part of the experience, and when you're role-playing as a hero out on adventures with people s-/he potentially grows close with... Yeah.
And, really, visual novels--in my limited experience--tend to be fairly stripped-down RPGs, mechanically, so it's not like those mechanics have no place in an RPG.