A-Un is a supporting protagonist in the anime/manga series Inuyasha. He is Sesshōmaru's beast of burden and his oldest travelling companion, having travelled with him longer even than Jaken. He is one of the only two yōkai in the series who is explicitly stated to be an herbivore. Despite traveling with Sesshōmaru for centuries, he has no name until Rin gives him one, calling the right head "A" and the left head "Un".
On their journeys, Rin and Jaken often rest on his back to fly over great distances. When Sesshōmaru leaves Rin in a safe place, A-Un stays with her as her protector.
A-Un is quite a benevolent and laid-back creature, subservient to Sesshōmaru and even to Kohaku, Rin (although this could be due to the kindness Rin has shown the creature) while only occasionally obeying Jaken, who sometimes has trouble motivating the demon to move; A-Un was implied to actually have little to no respect for Jaken in the 3rd movie when Jaken encouraged Sesshōmaru not to team up with InuYasha, prompting everyone (A-Un apparently included) to rearrange his face to change his mind, showing A-Un is much more intelligent than he looks and that he could understand the situation at hand. This also showed when he merited the two dog brothers' teamwork.
A-Un's benevolent nature may be due to the fact that he is one of the only two yōkai in the series who is explicitly stated to be an herbivore. A-Un is intelligent and is a sentient being; he also seems to have a sense of humor. The closest counterpart to A-Un in the series in terms of personality would be Kirara, a demon who also cannot speak but does possess a great deal of intelligence and loyalty.
Powers & Abilities
A-Un possessed the ability of flight in a manner similar to Tōtōsai's three-eyed cow yōkai Mō-Mō- an ability which is used to the advantage of Sesshōmaru when it comes to traversing great distances. A-Un typically carried Rin around on its back as she was not fast enough and did not possess the stamina to keep up with Sesshōmaru when they traveled.
A-Un could also shoot bursts of energy similar to lightning bolts out of its mouths. From the right head, "A", it fires beams of blue lightning to attack its enemies when it is roused into battle. The left head, "Un", fires green lightning which allows him to control clouds and possibly the weather. However, this ability has never been used to directly attack anything and it’s possible that it isn’t harmful.