Some of the later skills at the dojo are quite expensive (2,000,000 yen right now) so I've appreciated finding all the treasure I could. Maybee thats a trivial amount later in the game, (*SPOILER* I'm just about to go to the Dragon City to find out about the water dragon *END SPOILER*) but at the moment every bit helps. And once I obtained the waving cat statue, ink bottles became a useful addition. Since I no longer have to bother with going to get them, I can continue a fight or do a mass rejuvanation spree without stopping or worrying about turning into normal sucky wolf form - that super burning infinity sign technique can drain ink like nobody's business.