Aoi Rokusho is an anime-only character of the Naruto anime and the main antagonist of the first filler arc of the series, the Todoroki Shrine Race Arc. He was a Jonin of the Hidden Rain Village who had betrayed the Hidden Leaf in the past. Despite his lack of involvement in the manga, Rokusho was a relevant character to the story in the anime since he was one Sasuke Uchiha's drives for leaving the Hidden Leaf to join Orochimaru's side.
Birth, Treason, and Hidden Rain Jonin
Aoi Rokusho was born in the Hidden Leaf Village and grew into a Chunin-level shinobi and one of mentors of Idate Morino, younger brother of the Leaf Jonin Ibiki Morino. After his student had been failed while trying to take the Chunin Exams by his brother, Rokusho tricked him into stealing the Blade of Thunder Spirit that once belonged to Tobirama Senju, thr Second Hokage, and a secret scroll for him, promising he could be a Chunin in return, adding on it would be in the Hidden Rain Village after he had them. Though Ibiki and some Anbu Black Ops followed them, Aoi captured him and had his men killed, attempting to torture him into deciphering the secret scroll. However, Ibiki injured Rokusho and allowed Idate to escape, while also managing to reclaim the secret scroll. Rokusho, however, was able to keep the sword and went on to become a Jonin of the Hidden Rain.
Land of Tea Runion and DeathAoi Rokusho was hired, along with some Genin of his village, to help ensure the Wagarashi Family of the Land of Tea won the Todoroki Shrine Race that occurred once every four years so that they could continue their cruel reign of leadership of their port town. Rokusho ambushed some messengers being sent to the Hidden Leaf to hire ninja for his employer's rival family, the Wasabi, which failed as Naruto Uzumaki and his teammates were hired and sent to ensure the Wasabi racer, Idate Morino, won. Going with his employer's racer at sea, Aoi sent his men to ambush Morino and the others, but they were defeated by Naruto, managing to sink their boat and force them to swim to shore. There, Aoi reunited with Idate for the first time in three years, attempting to kill him, and later Naruto and his teammates when they arrived by the use of poison. He failed to kill them, however, and later tried again to kill Idate, with Naruto, closely followed by his friends, arrived and began to fight with him again. Rokusho easily overwhelmed both Naruto and Sasuke Uchiha at first, defeating the latter and throwing him over the cliff with Sakura Haruno, albeit after his Blade of Thunder Spirit had been cracked. Though he kept to upper hand at first, Aoi was defeated by Naruto when the latter struck the crack with his Rasengan jutsu, snapping the sword in half and sending the screaming Rokusho head first over the cliff to his death in the riptide-spinning waters below.
Rokusho was a very self-serving man, who felt no complete ties of loyalty to anyone and who trust nobody. He was cunning, having been able to trick Idate Morino into committing high treason with him by having him steal the Second Hokage's Blade of Thunder Spirit and a secret scroll, convincing him he could become a Chunin if he did, while not telling him it would be in the Hidden Rain Village. Aoi was very arrogant towards Genin, believing they had no shot at defeating him, especially since he had the Second's weapon at his side, which led to his demise by Naruto Uzumaki's hands.