Sora

is a monk who appeared in the first filler arc of Naruto: Shippūden.

Background
During the Nine-Tailed Demon Fox's attack on Konohagakure, some of its chakra were scattered throughout the village. Even though it was only part of the Nine-Tails' chakra, it was enough to make Sora turn into his four-tailed form. Sora's father, Kazuma, collected the chakra, and sealed it into Sora's body. As Sora grew up in the Fire Temple, he looked up to his father, later believing him to have been killed. One day he went berserk and destroyed the temple, a place otherwise believed to be an indestructible fortress. Afterwards, he was loathed by some of the monks of the temple, and soon began receiving the same ostracizing treatment that Naruto Uzumaki experienced while young.

Sora had trust issues, and was extremely inexperienced at showing his real feelings around other people because of all the lies and deceit he had faced.

Personality
He wanted to become part of the Twelve Guardian Ninja. He hated himself because of his powers, and became angry when people stared at him. When he first met Naruto, they hated each other, but eventually became friends. Sora did not like getting help from people, especially ninja.

It also seemed that, thanks to sharing the Nine-Tails' chakra, Sora and Naruto shared a bond, which explains Naruto's dream about the Fire Temple and Sora, and Sora's ability to sense that Naruto was in danger when Fūka was trying to suck out his chakra.

Abilities
Sora is a wind-natured chakra user, like Naruto and Asuma. He is able to manipulate wind to form powerful gusts capable of lifting and pushing away objects, or create chakra-infused wind blades capable of cutting through most materials. The pinnacle of his wind manipulation is to create a powerful claw composed of chakra-infused wind that he controls as an extension of his own arm.

He wields a tri-bladed death claw that he learns to infuse with chakra for a longer range of attack, which was refined further after training from Asuma. Asuma gave him a new blade made of chakra-enhancing metal after his old one was destroyed in a fight with Furido. With a style of taijutsu known only to the monks of the Fire Temple, Sora is also a very proficient close-range fighter, as shown from his ability to defeat several of Naruto's shadow clones.

Also, like Naruto, he has been shown to have high levels of stamina and chakra. Taking advantage of this, Sora's father, Kazuma, spliced his cellular make-up with excess chakra of the Nine-Tails to create a pseudo-jinchūriki. Sora was capable, although unwilling it seems, to transform into a miniature demon fox much like Naruto, but was weaker than Naruto in comparison. In this form, he had all the power and resistance to injure and attack to the likes of an unsealed Nine-Tails. After the battle with Naruto, all of Sora's demon chakra was expelled from his body, effectively taking away his ability to transform. The expelled chakra sought Naruto out as a host and, thus, the rest of the Nine-Tails' chakra now rests in Naruto.

Twelve Guardian Ninja arc
Naruto found Sora sparring with other monks, and it seemed to him that Sora was despised, so tried to befriend him, but was rejected. Sora, Naruto, and the rest of Team Yamato were soon sent to investigate a number of grave robbings of former members of the Twelve Guardian Ninja. Not interested in helping the team, Sora went off alone and found the enemy leader, Furido. When he discovered that he was their target, he questioned Furido about this, but started to grow angry when he received no reply. Furido taunted Sora until Sora unleashed his true powers, before informing him that he was planning to use the corpses to save the Land of Fire. After an explosion, Sora woke up only to find out that Furido had vanished, only leaving him a clue that he knew his father and that Sora resembled him.

Sora was assigned to go to Konoha with Team Yamato to replace an injured Sai. Naruto tried to show Sora around Konoha, but Sora went his own way, insulting those he came across. He later met Asuma, a man who had known his father and who offered to help him and Naruto with wind jutsu training. Although he proved skilled with the Chakra Enhanced Trench Knives, he learned that Asuma was the one who had killed his father, something that caused him great distress.

Later on, Sora tried to look for Asuma, and followed him to Danzō's interrogation. There he found out that Homura Mitokado and Koharu Utatane disliked Sora, and considered him unwelcome in the village, planning to kill him. Before Tsunade could make her decision on what to do with Sora, however, he was discovered and captured by ANBU members. Enraged that he was hated even in Konoha, Sora attacked Asuma, his arm once again assuming a demonic form. Sora fled and sought out Furido, who told him that the only way to avenge his father was to kill Tsunade. When he failed during the initial attempt, he returned to Furido, who revealed himself as Kazuma and used the Five Elements Unseal to release all of the Nine-Tails' power sealed within Sora.

Before Sora could do any serious damage, however, he was confronted by Naruto, who absorbed all of the Nine-Tails' chakra stored within him. After recovering in the hospital, Sora bid farewell to Naruto and Team Yamato, asking them to tell Asuma he apologized for his actions before leaving to travel the world.

Trivia

 * Sora's name means "sky" in Japanese.
 * Sora was usually seen with white sleeves for his uniform, but in some scenes they were black.
 * Sora's character seemed to be designed as a further example of wind chakra.

Quotes
סורה
 * (To Naruto) "I heard what I heard, so I came to help."
 * (To Naruto) "I've thought of a nice kaimyō for you."