Kakashi's Story: The Sixth Hokage and the Failed Prince

From Viz:

Vol 1: Kakashi Retsuden: The Sixth Hokage and the Failure Boy
When Kakashi sets off on a mission to the lush land of Redaku, he encounters its people suffering from a severe drought. The prince of Redaku can bring water to the land, but he has left his royal home for another village. When Kakashi locates the prince, he discovers a more elaborate plot long in the works that involves the fates of both Redaku and Konoha.

Vol 2: Sasuke Retsuden: The Uchiha Descendants and the Heavenly Stardust
Uchiha Sasuke heads for an astronomical observatory, far from the Land of Fire. There, he syncs up with Sakura, and together they dive into an undercover investigation in search of traces of the Sage of Six Paths! They discover a plan that goes beyond life and death, and a battle that will test this husband-and-wife team till death do they part.

Vol 3: Naruto Retsuden: Naruto Uzumaki and the Spiral Destiny
When Naruto is no longer able to use chakra, the shinobi of Konoha come together to help him. Even Orochimaru offers to assist with scientific ninja tools. While directing the people around him with all the dynamic ferocity of a mighty whirlpool, Naruto stands tall, facing this trial with an unbreakable spirit.