Kuromaru

is the ninken of Tsume Inuzuka. He is the only one of the Inuzuka ninken to be shown with the ability to talk.

Appearance
Kuromaru is an adult canine with a wolfish appearance. As his name suggests, Kuromaru's fur is black. He is missing his left ear, along with his right eye--over which he wears an eyepatch. He appears to have grown much larger in Part II than when he was seen in his brief Part I appearance.

Invasion of Konoha Arc
Kuromaru and Tsume, along with Hana Inuzuka and the Three Haimaru Brothers, assist in the village's defense during the invasion of Konoha, fending off invading Otogakure and Sunagakure ninja.

Invasion of Pain Arc
Kuromaru appeared again during the invasion of Pain. As Pain's Preta Path prepared to dispose of the previous Animal Path, Kuromaru and Tsume Inuzuka attacked it with Fang Passing Fang. The Preta Path used the old Animal Path as a shield and avoided the attack. Kiba and Akamaru joined them in the battle, but the Preta Path was summoned away before Pain crushed the village.

Trivia

 * The 'Kuro' in Kuromaru's name means the colour 'black', and 'maru' meaning 'perfection' or 'full circle' is a common suffix for Japanese male names.