gin

Gin is fiercely loyal to Don Krieg, carrying out any orders given to him without protest or hesitation, no matter how brutal or ruthless, earning him the nickname "Gin the Demon Man." This loyalty stems from a deep-seated fear of Krieg, as seen when he obeys an order to remove his gas mask and breathe in the lethal MH5 poison gas, fearing Krieg's wrath more than death itself. However, unlike Krieg, Gin possesses a sense of honor. He cannot bring himself to kill Sanji, the first person who ever showed him kindness by saving him from starvation.

Source: One Piece Wikia