Jinin Akebino (通草野餌人, Akebino Jinin) was one of the former members of the Seven Ninja Swordsmen of the Mist.

He was evidently very skilled at utilising Kabutowari, a blunt sword that consists of a single sided axe and a hammer joined by a leather strap, which is said to be capable of breaking through any defence. This is achieved by first striking with the axe, before hammering it through the remainder of the obstruction with the hammer, resulting in the axe functioning much like a wedge. The 'swords' construction still allows the weapons to retain their individual capabilities and thanks to Jinin's expertise, both the axe and the hammer can be exploited to their fullest.

Manga Debut: Chapter #522

Anime: Naruto Shippūden Episode #265

(Source: Narutopedia)