Dr. K-Ko  

Super Dr. K-Ko, ドクターケーコ

The main antagonist in the series is a scientist who frequently appears as a semi-regular character. She has expertise in the Netherworld and is determined to convince the scientific community of the danger posed by the four princesses, which she sees as an opportunity for her own personal gain. Dr. K-Ko seeks proof of supernatural phenomena to advance her status within the scientific elite, and believes that capturing or exposing the princesses would be the perfect way to achieve this goal. However, her plans often go awry.