Mangetsu Hōzuki

is the elder brother of Team Hawk member Suigetsu Hozuki. The third databook reveals that he and Suigetsu both trained with the intention of becoming members of the Seven Ninja Swordsmen of the Mist together, but their ambition was cut short by Mangetsu's premature death. Even though his abilities have not been demonstrated or even mentioned, this implies that they are similar to Suigetsu's and that he, like Kisame, Zabuza and his brother, primarily fought wielding a particularly large sword.

Speculations
Some fans suppose Mangetsu to be the former Jinchuuriki of The Three-Tailed Beast, depicted at the cover of the Chapter 420. The Jinchuuriki's eyes are purple like Mangetsu's brother Suigetsu's, he has the Kirigakure identification mark, and the flower on his sword is hozuki, whose name concurs with Mangetsu's surname. The Beast extraction would also explain his premature death.