Hakai Shido

Hakai Shido (破戒志度, Hakai Shido) is a rogue shinobi who originated from Konohagakure. During his time at Kirigakure, he was apart of an anti-terrorist group known as Utsukushi (美しさ). Hakai was very respected among the organization because of his control over Kurama, The Nine-Tailed Fox. While it did give the organization a strong advantage, it had it's drawbacks as well. Hakai soon lost control over the beast's power, and went on a destructive rampage through the village, killing most of his teammates in the process. He was eventually subdued by Hiruda, his partner and childhood friend. Not too long after the devastating incident, Hakai fled from Kirigakure, and was never seen again by the organization.

Background
Hakai wasn't a lonely child. He had many siblings and it was never quiet at home. He had two loving parents who were sometimes too busy to show their love for him, as there were many other children who needed their attention. Along the way, he met Hiruda, a young boy like him who was an only child. They found themselves hanging out with each other often and were, without a doubt, inseparable. Hakai's family never noticed that he was always gone, seeing that they were always distracted.

Genin Days
After graduating from the academy and becoming a Genin, Hakai's life grew tougher. His siblings were getting older, and that meant more chaos. Again, Hakai found relief when he found Hiruda. They constantly trained together and didn't mind stopping by Ichiraku Ramen every now and then. Hakai and Hiruda's skills were roughly on the same level, however, Hiruda was more intelligent than the young inexperienced boy. Hakai became more reckless and uncontrollable, making the two different from each other. Hakai secretly became jealous of Hiruda's skills, and tried to beat him at everything if he got the chance, but he was no match for Hiruda's intellect. Days before the chunin exams, Hakai trained hard so that he could defeat whatever that was thrown at him, until he met his grandfather, Izudamu Uchiha. Izudamu trained with Hakai for days, until it was time for the chunin exams. Hakai passed his exams with flying colors, and soon realized that his grandfather was the key to success.

Chunin Days
Hakai had passed his exams and went on to become Chūnin, along with Hiruda. The two became even more skilled, and Hiruda still outmatched Hakai by just a little bit so Hakai wanted to take it to the next level. Hakai trained with his grandfather more until he received a gift, the sharingan eyes. Izudamu had a storage room filled with them, from past enemies of the Uchiha clan. Hakai was excited, the sharingan was just what he needed to surpass Hiruda and become so powerful that his sensei would promote him to jonin. His dreams were cut short when he was requested by his sensei to spar Hiruda. While he did manage to keep up with Hiruda's taijutsu, he failed in the end. He went back to his grandfather, begging for something more powerful so that he could show Hiruda who really was the strongest. Izudamu saw the fire in his eyes and knew that he wanted to become strong, that he wanted to prove his worth, thus, making him turn to the only option left, The Black Nine-Tails (黒九尾, Kuro Kyūbi).

Hakai's Black Nine-Tails
Hakai now possessed the Black Nine-Tails, the darker half Kurama. When Hakai and Hiruda sparred again, Hiruda noticed a difference in his chakra. Hakai had grew ten times stronger than Hiruda, and even his sensei knew why. Hakai beat Hiruda for once, and he felt satisfied. Hiruda and Hakai grew distant from then on, only speaking to each other when needed, or when they had to work together. Hakai's grandfather approached him, explaining to him that the nine-tails was a powerful tailed beast who once destroyed Konohagakure. Hakai had become a little afraid now, he didn't want such a powerful monster inside of him anymore, but Izudamu told him that it would kill him if he extracted the beast from a child. Hakai kept quiet about the beast, at least until he got it extracted.