Naruto, after gaining the power of Ten-Tails, further learned how to control and manipulate that chakra to create the Tailed Beast Upa Rasengan, which allowed him and Sasuke to control Boruto by the latter's will. When Sasuke sent Boruto to be "watched" by Sasuke, this version of Boruto remained loyal to Naruto, not Sasuke, as Sasuke had ordered. When Naruto lost his control of Boruto and the damage he caused was reversed, Boruto declared his loyalty to Naruto as a genin. After the two genin were sent away to complete their training, Boruto reflected on leaving Naruto.
Sana recognized Naruto's Nine-Tails from his son. At the Falls of Truth, Sasuke first sensed a Nine-Tails chakra while he was practicing with Naruto. While he continued, he sensed the Nine-Tails' chakra in the distance. B then noticed the chakra, and approached it. While aiming to kill the Nine-Tails with his axe, B was hit by an attack. While still grieving for the loss of his son, he drew his kunai and used a Soul Saver Seal to absorb the chakra from the Nine-Tails. B then pulled Shikamaru from the chakra, and promised him he'd find a way to revive his deceased son.
Under B's supervision, Shikamaru began working on ways to revive his son. At the secret base, they turned on the chakra-absorbing devices to find the chakra and revived him. As Shikamaru reflected on the process, the device was destroyed by a massive energy, causing the group to know it was associated with Akatsuki. The next day, the two discovered that B's jinchuriki was a half-male, half-female body called Rura. B explained that while he was working on a way to resurrect Sasuke and Naruto as a jinchuriki, he needed an Ura Chuunin to produce a part to heal his son. d2c66b5586