This is a 2 part S rank. One part has you playing as Hiruzen Sarutobi (The 3rd Hokage) against the Nine Tail's. During this section you will jumping across the roof tops of a burning village hidden in the leaves while dodging attacks from the Nine Tail's. The main thing about this fight is dodging the tailed beast ball (energy attack from the mouth) attack by jumping around the village rooftops. The other thing is paying mind to the Nine Tails swiping at you with his claw, if you are too close for very long.
In order to hurt the Nine Tails you need to get to a rooftop near him that is glowing blue; at this point you can melee the Nine Tails' with an enlarged staff. Hit him a few times and then back away before he howls. If you get hit by it; it will send you flying but does minimal damage. You can also throw chakra charged shuriken by hitting + . It does minimal damage but it does keep you at a distance. You can also use Hiruzen's ninjutsu by hitting + ; this is a fire attack; again not a lot of damage but it allows you to peck at his health from a distance.
Through out the battle multiple people will come to your aid. You can activate that help by following the glowing arrow to a certain roof top and then press to interact with them. This initiates quick time events where the support uses their clan's special technique to attack the Nine Tails. First one being Choza Akimichi, Second being the Inuzaka clan, Third being a combo attack with the Nara and Akimichi clan and lastly the Yamanaka clan ordering the entire village to unleash an attack on the Nine Tail's. Once that has happened the fight with the Nine Tails is done.
Now for Minato's fight with The Masked Man. This is a standard 1 on 1 fight. Use your substitution jutsu's wisely to avoid his jutsus. Throw shuriken/kunai to block his shuriken/kunai throws. Try to use your substitution justus to create openings to hit him with your ninjutsu + and ultimate jutsu ++. Also try not run out of substitutions; if you are running low play keep away for a bit to let it recharge. This way you won't be stuck in a situation where you get stuck in a taijutsu combo or can't avoid his ninjutsu or ultimate jutsu.
Now once you beat The Masked Man and The Nine Tails; as long you maintained a good health bar you should get an S rank. This S rank is not very hard and should not pose a problem.