You earn Storm Points after every battle. You get Storm Points according to the amount of life you had left, time it took to finish the match and any type of bonuses received. You should get this well before completing everything you have to in Ultimate Adventure mode, however if you're impatient there’s a quick way to get 999,999 SP.
Go to Free Battle and select 1P vs 2P. Press and set the handicap all the way in 1P's favor. Select Naruto vs whomever and at the start of the battle use your Ultimate Jutsu - this should take off half of the opponent's health. Once you’re out of the animation, press to restore your Chakra with ramen and then charge a bit more Chakra and use your Ultimate Jutsu again, the attack should kill the opponent. This method only takes about 8-9 seconds on the timer and nets you well over 9000 SP per battle.