Rengoku is a mysterious kunoichi from Kimon Clan, with a unique body and talent for self-surgery. Rengoku can sew replacement or extra body parts to herself. She has four arms and a variety of stitch patterns across her body. Her arms stretch out to resemble spindly spider legs and she is viewed as a monster by local villagers.

She is obsessed with her brother to the point of incest. His death sent her on a path of vengeance toward Jubei, instead of focusing on collecting the Dragon Stone.