Gengetsu Hōzuki

He was the of Kirigakure.

Background
During his lifetime he had a mutual enmity with the Second Tsuchikage, Mū. Eventually both men ended up killing each other during a confrontation.

Appearance
The Second Mizukage is an individual with a fairly tall and slender stature in comparison to others. His elongated face is accentuated by his relatively long light colored hair, worn in a combed back style, and the presence of a small dark colored goatee and thin mustache. Due to the effects of the Summoning: Impure World Resurrection technique, he has black sclera and white irides.

His typical attire consists of a long sleeved, high collared robe, which has the pin-striped pattern that is common amongst the shinobi of Kirigakure. This article is worn over a dark colored suit, with an equally dark sash wrapped around his waist.

Abilities
Although he has yet to be observed in combat, the simple fact that he was able to kill Mū, albeit at the cost of his own life, stands as an appropriate testament to his proficient skills. This is because even some of the most notable shinobi of the Allied Shinobi Forces greatly feared that no one but Ōnoki, a former pupil and possessor of the same kekkei tōta as Mū, would be able to stop the former Tsuchikage, suggesting that the Second Mizukage's combat capabilities are truly fearsome.

Shinobi World War Arc
When Mū, despite his camouflage, is detected approaching the Fourth Division, Kabuto Yakushi has Mū summon three other Kage to provide support. Amongst these Kage is the Second Mizukage, who immediately recognizes Mū. When told that he has been resurrected, the Second Mizukage is confused by news of his own death until Mū reminds him that they killed each other long ago. Mū's explanation is confirmed when the Second wants to kill Mū again but his body wouldn't obey his desires, a sign of the control their summoner has over them.