[quote=@Grey]
I'm putting my money on Dino/Asuka.

All of it. My whole $11.60
[/quote]

I think that would be too convenient. And yes she could learn more whip stuff but she should learn from somebody with a bigger range of weaponry and stuff that could test her skills better. 

But yeah... I'd hope for Hibari. Or 20YL Lambo. 
Or Gokudera. Or Yamamoto. 

OH! OR OR OR! Fucking Ryohei! Love that guy and adult him would be a badass tutor. Cause he would probably explain things a bit better. Plus he could heal her when she gets hurt... And yeah... His close range is best.