Sakazuki, Admiral Akainu (formerly known as Vice Admiral Sakazuki) is an Admiral in the world of One Piece, one of only three to hold such a position and subordinate only to Fleet Admiral Sengoku. In English, his name means "Red Dog." Sakazuki became the new Fleet Admiral during the timeskip, succeeding Sengoku in his role.

Akainu is a firm believer in "Absolute Justice," going as far as destroying the refugee ship simply due to the possibility of even one scholar sneaking on board. His logic is that if even one of the scholars of Ohara had escaped with it, the mission would've been a failure, much to the dismay of Aokiji, who called him a fool for overdoing things. As an Admiral, Akainu is able to command vast number of Marine troops that are under his rank. Most of all, he has the ability to order a Buster Call attack on any island. In addition to this, given that he holds the same rank as Kizaru and Aokiji, it can be assumed that he commands comparable fighting abilities to those two.

He has the devil fruit ability where he is able to transform his body into magma.

(Source: One Piece Wikia)