Naruto: Clash of Ninja/Akamaru

Akamaru is Kiba Inuzuka's ninja dog, best friend, and constant companion. At the start of the series, Kiba carries Akamaru around on his head or inside his jacket. By Part II of the Naruto storyline, Akamaru grows large enough for Kiba to ride atop his back, but since Kiba spends so much time with Akamaru, he fails to notice this drastic difference. With his heightened sense of smell, hearing, and the ability to detect others' chakra levels, Akamaru acts as a valuable tool for Kiba in hostile situations. To help Kiba keep track of opponents, Akamaru can urinate on them, giving them a strong odor that can easily be tracked. In battle, however, he relies on Kiba to provide the chakra for the combination attacks they execute, which requires Akamaru to transform into a clone of Kiba.