360 Degrees of Vision: The Byakugan's Blind Spot

is episode 116 of the original Naruto anime.

Synopsis
Kidōmaru manages to shield himself from Neji's attack, and flees to the safety of the neighbouring trees. Deciding to attack Neji from a safe distance, Kidōmaru advances his cursed seal to its first level before sending multiple spiders to attack Neji from his personal summon. Neji is able to repel them all, although Kidōmaru notices a delayed reaction in some of Neji's blocks. He theorises that Neji's defences have a blind spot, and continues to attack him from this blind spot. His theory is proven correct when Neji is unable to block the attack he sent. Believing himself to have found Neji's weakness, Kidōmaru prepares to finish the battle.