Sora's Jinchūriki Forms

When the Nine-Tailed Demon Fox attacked Konohagakure, it left a lot of chakra in the air, which was later gathered by Kazuma, one of the 12 Guard Ninjas of Fire, who wanted to create a Jinchūriki weapon for Konoha. After five years of experimentation, he finally was able to implant the demon fox's chakra into the cells of his son, Sora. Because Sora does not have the Tailed Beast sealed within him, but only has his cells combined with its chakra, is he refered to as a Pseudo Jinchūriki.

Jinchūriki Form
Unlike Naruto, who has a stable and controlled combination of his own chakra and the Nine-Tailed Demon Fox's chakra, Sora can't control the chakra added to his cells. To stabilize this, \his father applied a sealing jutsu on Sora several times to keep him and the chakra under control.

When Sora feels frustrated or is in a state of great anger, the chakra can change his right arm into a demonic form. It would seem that he is not aware at all about the change of his arm, and has first noticed it when his father told him.

Because the Nine-Tailed Demon Fox is a chakra monster, a small amount of its chakra implanted within Sora can react to the chakra of the real Nine-Tailed Demon Fox inside Naruto as it somehow called out to him when Naruto was about to be killed by Fuka. Like Naruto, when the chakra is released from Sora in large amounts, a demon fox's cloak forms around Sora, initially with one tail. In addition, like Naruto, during this transformation, Sora's hair becomes wilder, his canines more pronounced and his eyes turned to slitted foxlike eyes. Due to being a pseudo-jinchuuriki, Sora has some different features from Naruto in a similar state (besides the arm) including spiky projections growing from his cheeks.