Rien

About

Rien is Ouga's younger brother. He is captured while trying to rescue Yuuri, and kept as a prisoner aboard Kuuron's ship. He refuses to eat the food prepared by Kougyoku, the ship's cook, for fear that it might be poisoned.

Note: the fourth prince in Ouga's family is listed in Ousama Game to be Ryuuga, while in Kaizoku Game he is listed to be Rien. Both have very different personalities. It it likely that this is a mistake on the mangaka's part.