You are part of the Straw Hat crew, and like Chopper, you have knowledge of medicine, making it easier to care for the injured when Chopper transforms.

After Hody's defeat you had to help take care of the injured since Chopper couldn't move. After you treated the princes Ryuboshi and Manboshi you approached the oldest merman, Fukaboshi, who by the way was in a bad state.

"I'm sorry for the trouble, human. I'm very grateful that you protected my sister."

He spoke while looking at you bandaging his body with an expression of gratitude.