Homura Karasuki

Current king of the Karasuki kingdom, Ayame's father and Rio's grandfather, in the past he realized Zen's and Ayame's feelings for each other and even though he wished to let them to get married he wasn't able to because the nobles from other faction's wouldn't have seen with good eyes a marriage between a princess like Ayame, despite her post in the succession list being low, and an upstart like Zen, despite him being famous as hero of war in the whole kingdom, after the ceasefire incident he ordered Zen and Ayame to escape together while pretending to accept the demand from the Rokuren kingdom's prince of turning them over, them with the time that he gained with his charade he made the preparations for winning the war against the Rokuren kingdom.

(Source: Seirei Gensouki Wiki)