Gennō's Son

He is the unnamed son of Gennō.

Background
Thirty years prior to the start of the series he died in a battle defending Kagerō Village. His father Gennō had warned him not to follow his example and become a ninja, so when the boy died he blamed himself and decided to take revenge on Konohagakure. Gennō planted exploding tags all around the village but he never detonated them because his village was destroyed.

Trap Master Arc
When Gennō came back 30 years later to finish what he had started. Naruto, his attitude, his dreams and his good heart reminded Gennō of his son and he gave up his plan of destroying the village.