Hoshigake Kisame(In 2 Player vs. mode) - Finish Kakashi Gaiden.

Kakashi Gaiden(Story) - Complete all missions(Including S Ranks).

Restore Chakra - During the Loading screen if allocated enough time to move the right thumbstick enough in a circle. A Blue Chakara Ball will pop-out and if you notice your unfilled Stamina / Chakara Bar. It will refill a little about 25% worth everytime you do this. Between Loading screens with the Konoha Symbol in the lower right corner.

Uchiha Itachi(In 2 Player vs. mode) - Finish Kakashi Gaiden.

Unlock S Rank Missions - Complete the game once.