A-Un

Ah-Un (阿吽 ,A-Un) is Sesshomaru's beast of burden. He is one of the only two yōkai in the series who is explicitly stated to be a herbivore. Despite traveling with Sesshomaru for centuries, he has no name until Rin gives him one, calling the right head "Ah" and the left head "Un". Ah-Un can fire yōkai energy from both mouths. The right head shoots blue beams of lightning, while the left shoots green lightning that can control clouds and possibly the weather. A grey cloud-like gas trails from his legs in flight, similar to Kirara's flames.

On their journeys, Rin and Jaken often rest on his back to fly over great distances. When Sesshomaru leaves Rin in a safe place, Ah-Un stays with her as her protector. He saves Rin from a group of lesser demons while she is collecting herbs to save Jaken from being poisoned by Naraku's Saimyōshō. Ah-Un also defeats many of Setsuna no Takemaru's zombie warriors in InuYasha the Movie: Swords of an Honorable Ruler.

Personality
Ah-Un is quite a benevolent and laidback creature, subservient to Sesshomaru and even to 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. Ah-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 a herbivore. Ah-Un is intelligents and is a sentient being; he also seems to have a sense of humour. The closest counter part to Ah-Un in the series in terms of personailty would be Kirara, a demon who also cannot speak but does possess a great deal of intelligence and loyalty.

Relationships

 * Sesshomaru - The Dog Demon Lord in control of Ah-Un. Ah-Un has been travelling with Sesshomaru as a servant for a longtime, longer than his vassel Jaken and especially longer than his most recent travelling companion Rin.
 * Rin - The young human girl travelling with Sesshomaru has a special relationship with Ah-Un. Rin named the demon and cares for it, as such Ah-Un looks after Rin in turn, rescueing her and allowing her to ride on it's back. Ah-Un has saved Rin on a multiple occasions. The two most memorable examples are when he her from some lesser yokai while she is collecting herbs to save Jaken when he is poisoned by Naraku’s miasma and when he protected her from the zombie warriors in the third Inuyasha movie, Swords of an Honorable Ruler.
 * Jaken - The demon vassel of Sesshomaru has a somewhat strained relationship with Ah-Un, apparently struggling to control the demon unlike Sesshomaru and Rin who Ah-Un willingly obeys without question.

Abilities
Ah-Un possesses the ability of flight in a manner similair to Totosai's three-eyed ox yōkai named Mo-Mo (猛々) -- an ability which is used to the advantage of Sesshomaru when it comes to traversing great distances. Ah-Un typically carries Rin around on it's back as she is not fast enough and does not possess the stamina to keep up with Sesshomaru when they travel. Ah-Un allows Rin to ride on it's back likely due to the fact that Rin cares for the creature a great deal; Ah-Un has saved Rin's life several times and has helped her to escape certain dangerous situations.

Ah-Un can also shoot bursts of energy similair to lightning bolts out of it's mouths to attack it's enemies when it is roused into battle. From the right head, which is Ah, he fires beams of blue lightning. His left head, Un, fires green lightening which allows him to control clouds and probably the weather. However, he's never used his green lightening to directly attack anything and it’s possible that it isn’t harmful.