Nikaidou is Kaiman's present companion, she owns the Hungry Bug, a family restaurant in The Hole. Nikaidou found Kaiman after his initial transformation, and has befriended and aided him ever since. They, together, hunt down magic users who enter The Hole, and try to locate the one who inflicted the transformation on Kaiman.

She is a Lamia, a half human, half snake sub-species. She is the first to be Kimihito's ward when the cultural exchange began. She is sweet, naive and a carefree individual. She has a habit of being clingy when she sleeps. She's very ticklish when one holds the very tip of her tail, which is why Kimihito exploits that weakness in order to get out of her grip.