During the first Naruto-Sasuke battle at the Valley of the End, just as Naruto and Sasuke fight to the bitter end, a strange earring appears beside them. Under its influence, their bodies move against their will and slam into each other.
Their collision unleashes a tremendous storm.
When the storm subsides, a man bearing the features of both stands in its place. Facing the Konoha Ninja pursuing him, he declares:
“I'm neither Naruto nor Sasuke. I'm the fusion of the two of them, and my name is Narusuke.”
“Now, let me see how strong I am!”
As soon as Narusuke finishes speaking, he opens his Three-Tomoe Sharingan, and orange-red chakra appears around him.