The Ultimate Jutsu is a special kind of move you can perform in Naruto Storm 3, which takes the form of over-the-top animations—you know the kind you'd see in the Naruto Shippuden anime or any other over-the-top Japanese anime with explosions and fighting and destruction the scale the likes of which you rarely ever see.
Like the special moves you perform in turn-based JRPGs, you can expect the entire world to shake as these characters perform their Ultimate Jutsu upon their most unfortunate opponent. These include Tailed Beast Boooomb, Lightning Straight, Cat Fire Bowl, Rough Sea Spume and more.
Performing these moves doesn't come easy and it's not one you can do at the start of the game. Like previous Naruto Storm titles, you can only perform these special moves well into a battle, and they take up a full bar of Chakra to use. Keep in mind that each character's Ultimate Jutsu may have different Chakra requirements.
If you have the necessary amount of Chakra to perform the action, simply stand a few feet away from your opponent and activate the move by keying in the right combination of buttons. Previously in Naruto Storm 2, all you had to do was press Triangle Triangle Circle and make contact with your opponent to unleash the Ultimate Jutsu upon them.
Then just sit back and watch the fireworks.