It was Obito Uchiha

Summary
Naruto reaches out his hand to Obito. However, instead of holding his hand, Obito tried to strangle Naruto, saying he had no regrets for everything he had done so far. Naruto punches Obito aside claiming he was not worthy to be a Hokage. Obito begins to see more of his old self in Naruto. Naruto then tells him that Rin wanted to look forward to "Obito Uchiha", not what Obito has become now. Obito remembers his past with Team Minato as he struggles with his inner turmoils, meanwhile Naruto forcefully grabs Obito's hand warning the Uchiha to not underestimate the power of everyone. In the real world (out of Mental World), the shinobis' attempts to pull out the Tailed Beasts were successful. Naruto and Sasuke, losing their armor-clad chakra shroud after winning the struggle, finally defeat Obito, who looks up to moon and grieves that he could not fill the hole in his heart.