Kou's Dungeon Capturer

It was mentioned in the previous episodes that Kou Empire has five dungeon capturer. The first one who was introduced in both anime and manga was Ren Hakuei, followed by her sister, Ren Kougyoku.

In episode 23, the three other dungeon capturers were introduced. 

Ren Hakuei, the first Imperial Princess

Ren Kougyoku, the eight princess

Three other capturers are Kou empire's princes; Ren Kouha, Ren Koumei and Ren Kouen.

Check out the princes, they have red hair,