Naruto - Season 0 Episode 2 : Naruto OVA 2: Protect the Waterfall Village! 2007

It's summer and Naruto and gang are doing missions. Their newest mission is to escort the leader of the Hidden Waterfall Village. But when Kakashi is called back to Konoha for an emergency jounin meeting, he leaves Naruto and gang behind. At the same time, an attack is initiated on the Hidden Waterfall Village, led by a missing-nin, and its former strongest jounin is executed. All of this is an attempt to get the "hero water", which multiplies your chakra tenfold in exchange for your life. Naruto and the gang are forced to do battle with the enemy in order to rid the Hidden Waterfall Village of its menace.