|Nickname:||The Mountain Wind|
Kaku, is first seen as one of the five foremen of Galley-La Company's Dock One and specializes in mechanics diagnostics and housecalls. It was Kaku that inspected the Going Merry and informed the Straw Hats that it was broken beyond repair.
He has strong legs which help him in running fast and jumping for great distance over the cityscape in order to finish ships' checkups quickly.
SpoilerHe is also a member of the CP9, who have the power of the Ushi Ushi No Mi Model: Giraffe (Cow Cow Fruit Model: Giraffe) which also reflects his favorite animal, the giraffe, as stated when he is made fun of his devil fruit power.
Later, before uncovering his mask, he uses a technique called Storm Leg and cracks the wall that Luffy got traped in.. which shows how strong his legs are.
Although he is one of the CP9, it seems he has a sense of honor and adventure, enough to match Luffy's which is clearly seen at the time of his defeat, he remembers the fun he had as a carpenter and flying through the cityscape.