Rakuyou is the commander of the 7th division of the Whitebeard Pirates. His name was revealed in a SBS of Volume 58.

He is a mustached man with dreadlocks. He wears a typical outfit consisting of a light coat, a black vest under an unbuttoned shirt, a standard pirate sash, square-patterned pants and standard boots. His outfit most notably includes a bandanna bearing Whitebeard’s mark. He is often seen wielding a unique spiked ball and chain that has a face at the end. This weapon vaguely resembles the Chain Chomp enemy from the Super Mario franchise in design.

(source: onepiece.wikia)