Werewolf Clan in Naruto! :)
Long ago, around the Sage of the Six Paths time, there were beings who walked the Earth along with the Humans. These beings were known as the Demon Tribes or Demon Clans and they were often at war with the Humans due to the fact that they worshiped the Ten Tailed Menace, The Juubi, and despised the Sage himself for opposing their precious God.
During the Gigantic Battle that pitted the Sage against the Juubi, certain Demonic Clans ran into battle against the humans. Among these clans was the infamous werewolf clan who were in fact ordinary humans that were experimented on by the Wolf Demons who had gone extinct over a hundred years earlier. These demons gave the humans pieces of their Dna in order to create more Wolf Demons in order to preserve their tribe but the result of the experiments turned out to be a failure to them. Instead of the humans becoming full wolf demons, they became merely half human and half wolf. The humans acquired the ability to transform in large versions of humanoid wolves and in their transformed states, they acquired incredible amounts of speed, strength, healing, stamina, and chakra levels. It was said that during the full moon, the transformation was far mroe powerful due to the fact that the virus reacted to the Moon's Rays.
In a gigantic battle against the Humans, the Werewolves ripped through Human ranks with ease. As they shred through the army of Humans who opposed them, the Sage of the Six Paths flew into battle after having sealed the Juubi. The Sage saw the destruction the Werewolves and other demons had caused and immediately sealed away the entire clan away deep into the ocean. Although the Sage had Sealed the Werewolf Clan, many humans began to study the Demonic Clan in order to understand their powers. Some Humans even started to practice the werewolf ways of combat. After hundreds of years, the Inuzuka Clan was born. They use the quick claw slashing, fang plunging, four legged battle tactics that the demonic clan did. However, Copying an art not always gets you the same results. Although the Inuzuka Clan was successful in becoming strong battlers and trackers, they were nothing compared to the true Werewolf Clans of the past. Kiba himself has remarked that even a young werewolf would have out sped one of his good friends Rock lee in Gates Mode and Kakashi has said that if the myths are true, a single werewolf could be at Tsunade's level of strength.
Today, Tidus Inuzuka, who has been kicked out of his clan for being too "barbaric" on the battlefield, has traveled for years and searched endlessly to find the ancient site of the Wolf Demon's Labs that created the first Werewolves. Tidus finally found the the lab deep within a cave not too far away from the Village Hidden in the Sand. It turned out that Deidara's invasion had actually caused the opening of the lab to show up due to fact that his explosions caused severe vibrations that made the entrance pop up. Tidus searched the lab and found the original formula that the Wolf Demon's had used on their human victims. With the Formula, Tidus grabbed viles of Wolf Demon DNA and ran out in search of the one man that he knew could put the formula together.
Having the best nose in his clan, Tidus found Orochimaru, much to the latter's surprise. Orochimaru, being impressed by the tracking skills of Tidus decided to actually toy around with the formula to see if he could truly bring back the Werewolf Virus. But Orochimaru was not only going to reactivate the virus, he planned to make it his own. By combining the virus with his own cursed seal marks, Orochimaru bit Tidus. Tidus, not having known Orochimaru tampered with the virus began to change in dramatic ways. His hair turned from black to white and his years began to enlarge. His claws became sharper than swords and he found that he could smell and hear thousands of times better. Being consumed by the overwhelming sounds and smells, Tidus ran from orochimaru's lab in pain and ran all the way to get the Wolf demon's lab near the Sand Village .He was confronted by the Kazekage Gaara himself who had been training in the desert. Gaara told Tidus to surrender because he was trespassing but Tidus saw Gaara as a threat and began to attack Gaara. Gaara, being extremely impressed by his unusual opponent's incredible speed and agility began to use the entire desert to bury the now demonic member of the INuzuka Clan. Gaara was in awe. never before had he seen someone of the Inuzuka clan battle like that. He had seen Kiba from the leaf village battle Naruto and it was nothing compared to this guy's ability. What was worse was the fact that this guy seemed to look a lot different than his clan mates. But Gaara quickly stopped his thought process for deep beneath the sand, Tidus had begun transforming into the full werewolf. Tidus ripped his entire body out of the sand and rushed at Gaara so fast that even Gaara's sand was not able to form a shield to protect Tidus from stabbing Gaara in the stomach with his incredible claws. Gaara, now on his knees looked at the Demon in Front of him. The Demon Howled and said in a voice that was mixed with growls, "The werewolf Clan lives"