Kansho

Kansho is an anime-only character that appeared in the Adventure of Nebulandia special. He is an undercover Marine who posed as a member of the Foxy Pirates along with Komei and Dojaku. Per Komei's plan, however, Kansho stayed behind even after the other two revealed their allegiance in order to betray Luffy and Foxy.

(Source: One Piece Wikia)