Akamaru is Kiba Inuzuka's nin-dog (ninken), best friend, and companion.
In Part I, Kiba carries Akamaru around on top of his head or inside his jacket. In Part II, Akamaru grows large enough for Kiba to ride on his back, a difference Kiba fails to notice due to the amount of time they spend together. Akamaru's heightened senses, such as smell and hearing, along with Kiba's ability to communicate with him, make him a powerful tool for gathering and sharing information; he can also sense chakra with his nose, so he can judge an enemy's strength and warn Kiba if they are particularly powerful. In combat, Akamaru typically takes Kiba's form (albeit having a much more feral appearance) upon Kiba's use of Beast Human Clone (Jūjin Bunshin; English TV "Man Beast Clone"), or combining with Kiba into a single entity in more desperate situations. Because Akamaru lacks his own chakra reserves Kiba performs many of the jutsu that Akamaru takes part in, though Akamaru is able to contribute when it comes to physical attacks. Akamaru can also use Dynamic Marking (Dainamikku Mākingu) by peeing on a target with great accuracy, allowing either Kiba or Akamaru to easily find the target by scent, particularly when fused together.
- Aka means red, but can also mean baby. -maru is a suffix for Japanese male names. So Akamaru can mean "baby boy" or "red boy."
- His favorite food is the special dog food Kiba makes.
- Akamaru is not to be confused with Kakashi Hatake's nin-dogs. Akamaru is an Inuzuka dog and is not a summoning.
- Akamaru is an integral part of Kiba's fighting style and accompanies him in battle in every game he appears in. In Clash of Ninja 2, Gekitou Ninja Taisen 3, and Gekitou Ninja Taisen 4, he is an unlockable character on his own as well.