This is a large map with several closed rooms. The only way to reach the other rooms is by reaching the stairs. If there are enemies guarding it, you have to defeat them first to gain access. The general location of the stairs will take you the nearest room from it. That said, you have to divide your troops to two groups in order to cover all rooms. Also, other units can’t use the stairs if there’s a unit blocking it from the other side.
There are also two chests in two separate rooms. Unfortunately, none of the enemies are carrying any key and since you only have Niles as the character capable of unlocking these, you have to protect him and move him on both rooms. On the brighter side, this mission will just require you to defeat the boss, Hinoka, to complete. The chest to the NE has an Enfeeble inside, while the NW chest has a Spirit Dust.
Key Hoshidan retainers will be guarding each room, along with their same class. Rinkah and her oni savages are found in the SE, Setsuna and her archers to the SW, Azama and his diviners on the NE, and Kaze and his Ninjas on the NW. The middle room has paired samurai units but with no special characters.
Before moving your characters in the next rooms, make sure to check the enemies' attack range to avoid getting caught off guard after you emerge from the stairs. There are also special dialogues if you attack the key characters using your avatar. Fight your way through the rooms until you reach Hinoka. Surprisingly, her attack range is quite small for a Sky Knight, so you have the chance to bring all your units inside the room then prepare for an all-out attack. After defeating Hinoka, Kaze will join your ranks.