Castor is a reserved and aloof prince of the Rome Empire. He doesn't often attend nobles gatherings, earning him the nickname of the Prince of Sun. His power, the power of light, strikes fear in the hearts of all, making him a daunting figure in the court. Only on special occasions, such as the choosing of a crown princess, would Castor be seen. On such occasions, he would personally judge the abilities of the chosen princesses of the different monarchies.