After a successful rescue mission in Izumo, you encounter Kitsune on the way to the Nohrian capital.
Preparations Before the Battle
Keaton has strong attacks against beasts, but since he is a beast himself, he will be more vulnerable as well, because some of the enemies here also have strong attacks against beasts.
Your mounted and flying units will be more vulnerable to many of these enemies as well.
Weapons such as the Beastslayer and Hunter's Knife will come in handy here.
At this point in the game, your units will start reaching level 20 if they haven't already. They can't level up beyond 20 in their base classes, so be sure to use Master Seals on them to turn them into an advanced class.
Rout the Enemy
The enemies in this battle can turn themselves into illusions for one turn. While in illusion form, they cannot attack, and you cannot attack them. Illusion enemies will be marked with a green leaf in front of their map sprites. They will return to normal after one turn, but they can become illusions again throughout the battle.
The illusion ability enables enemy units to reach your units without taking any damage.
Be aware that the enemies here can walk through the water.
The first wave of attacks will come from the north, so be sure to deal with that threat first. After all of the northeastern enemies are gone, start fighting the enemies to the west. Stay out of enemy range whenever possible to try to prevent the enemies from swarming everybody.