Kashii is one of the two giants who guarded the front gate of Enies Lobby.
As a giant, Kashii is not only many times larger than a normal human but also equally stronger. This was demonstrated when he faced the Kairiki Destroyers from the Franky Family, showing that any mere human, regardless of strength or size, would struggle in battle against them.
Kashii and his partner Oimo are natural-born fighters. Ultimately, it took the combined efforts of the best fighters from Galley-La and the Franky Family, along with assistance from Sodom and Gommorah, to defeat both Oimo and Kashii.
Source: http://onepiece.wikia.com/wiki/Kashii
