"The Battle Over the Barrier" (結界攻防戦, Kekkai Kōbōsen) is episode 105 of the Naruto: Shippūden anime.
Guren and Kabuto return to the lake where the latter attempts to feed Yūkimaru many pills. Knowing that the pills would come at the cost of Yūkimaru's life, Guren offers to deal with the tailed beast without Yūkimaru's involvement. Kabuto relents, but only if she follows his orders, and sends Rinji to relay his orders when the time comes. As she waits by the clifftop for Rinji, Kabuto brings Yūkimaru to an adjacent clifftop, with a view of the Konoha shinobi attempting their Four-Corner Sealing Barrier. He reminds Yūkimaru that Guren is willing to tackle a tailed beast all on her own just to save him, and that she may die from the effort.
Rinji approaches Guren and notifies her that the two people guarding the fūinjutsu team is a weapons-user and a taijutsu expert. Knowing her chakra is limited, Guren offers herself as bait to draw the attention of the two guardians while Rinji is to take out the sealing barrier. Lee and Tenten are surprised to see the Crystal Release user in front of them, as they had believed that Kakashi's team had dealt with her. Using her jade crystal blades on her forearms along with her Crystal Armour, she proves to be a formidable opponent for the two. She manages to distract the two while Rinji heads towards the sealing team, who are defenseless, only to be repelled by Naruto and Gamatatsu's Wind Release: Toad Gun. Lee is overjoyed to see Naruto, who had summoned Gamatatsu and Gamakichi. Shino is present as well, who attempts to use his bugs against Guren's crystal, only for it to fail against Guren's Crystal Release: Tearing Crystal Falling Dragon.
However, the tide of their bout turns when the Three-Tails manages to break out of its barrier. Guren tells Rinji to retreat, as their job of breaking the barrier has been successful. As they attempt to flee, the Three-Tailed Turtle uses his Water Release: Great Water Mass Bullet to destroy Guren's crystal dragon and sent her to shore on an island; Naruto and Shino are sent underwater while Gamakichi and Gamatatsu dispel themselves; Lee manages to save Ino as he reaches land. Yamato and Kiba meet up with Kakashi and Sai, with the latter team revealing that they had failed to defeat Guren. However, all four of them hear the cries of the tailed beast and realise that trouble is in the air. Meanwhile, Yūkimaru spots the Three-Tails about to harm a winded-out Guren and taps into his Three-Tails Chakra: Release to control the beast and prevent Guren's death. As Rinji spots Yūkimaru, it turns out that this was Orochimaru's plan all along - he knew that Yūkimaru would not unleash his true power while being forced to do so, and would only do it to protect a loved one, hence why he tasked Guren to his protection, knowing a bond would form between them. In the meantime, Tobi of the Akatsuki moves fleetingly around the perimeter as he observes the Three-Tails, gleeful that he has truly located it after all.