After capturing the Great Wall of Suzanoh, you must defeat Hinoka's troops.
Preparations Before the Battle
There will be many flying enemies in this battle, so be sure to include plenty of bow-wielding units in this battle.
There are several Dragon Veins in this map. They will decrease the movement range of flying units (both yours and the enemy's) and increase the movement range of non-flying units (both yours and the enemy's). However, Hinoka is standing on a Dragon Vein that has the opposite effect. Hinoka's Dragon Vein doesn't disappear after use, so she can do this as many times as she wants.
Send a royal unit near a Dragon Vein to be ready to counteract Hinoka's Dragon Vein when she uses it.
Flying enemy reinforcements will appear frequently, so stay in the southern half of the map and have your archers kill those flying enemies for several turns. Be sure to send some of your units to the southwest to kill the enemies on the small island there.
After several turns of fighting flying enemies, you can start going northwest. Azama has a Hexing Rod, which can cut a unit's HP in half. Try to stay out of his staff range while dealing with Setsuna and making your way to Hinoka.
After you defeat Hinoka, you can stand on the seize tile that she was standing on, and choose Seize to end the battle.