Akamaru (赤丸, Akamaru) is a nin-dog (忍犬, ninken) from Konohagakure's Inuzuka clan. He is Kiba Inuzuka's partner, as well as his best friend and companion. He is also a member of Team Kurenai.
Akamaru has been described as active and devoted. This can be seen from his interactions with people especially his best friend and companion Kiba whom he has always been with since the two met. They often spend their time going on walks, or more accurately, running through trees chasing one another. His devotion is most often seen when Kiba is hurt in battle, Akamaru will immediately run to his side.
In Rai no Sho, a story from Akamaru's point of view reveals much of his personality. Akamaru is revealed to have a humorous thought process by erroneously explaining something, but then immediately correcting himself. He has a very scientific thought process about humans, thinking they enter estrous too late in life when they should be focusing on being shinobi instead of finding a "mate". It's also revealed Akamaru is very overprotective of Kiba as he immediately tried fruitlessly to pull his master away from Tamaki when he realised the two had a strong mutual attraction to each other, as he didn't want Kiba to shy away from his training in favour of romancing Tamaki like "the others". It is also revealed that Akamaru retains a canine thought process as he calls female humans "bitches", like a female dog. Whether is actually insulting the women (given his angry disposition at the time) or if he always associates women like this is currently unknown.
In the epilogue, Akamaru had grown old and took delight in just napping most of the day and playing with his puppies. When prompted by Kiba to back him up, he mocked Kiba's notion that he turned down the Seventh Hokage seat, giving a sly smirk.
Akamaru has the ability to sniff out the level of an enemy's chakra.