I'm pretty sure Ryo is used to buy items from the Time Turner Old Woman, but she just tells me to use the signs.
Yes, I did create that game on the Vita you probably never heard of.
Soul is like your XP/Battle points. Ryo is like dollars, Bu is like cents. At least, I think that's how it works and yes, you use the Ryo to buy items from the little old lady.
Exactly, Bu is the equivalence of an american quarter, In other words, 4 Bu = 1 Ryo
I'm sure they will, either something like excusive rewards unlocked only by gaining souls ( XP ) or perhaps they'll set up a level system for VS missions just like with Peakvox Ninja. all we can do for now is wait and see.