In this map, you'll meet Kaden (recruitable character in Birthright) and the rest of the Kitsune clan.None of the kitsunes can't be captured. There are no dragon veins in the area but there's a tree to the north that you can break down to create a makeshift bridge across the river. There are also two Kitsunes to the NE and SW carrying a Talisman and 5000g. Kaden himself is carrying a Beaststone+. The objective of this mission is to eliminate all enemies.
Some of the kitsunes have a couple of dangerous skills called Pass and Beastbane. Pass allows them to pass through enemy spaces, enabling them to pass through your defenses and target your weaker units like healers and spellcasters. Beastbane will allow to deal bonus damage against riders and fliers. All of them are melee fighters so if you can engage them in ranged Combat during your initiative, that will be much better.
As soon as you start the battle, the game will warn you about the illusions the enemies will make. Illusions can't hurt you and you can't hurt them as well during the current turn. During their turn however, these illusions can turn to the real thing and hurt your troops. That said, always keep troops' HP up if you can help it. Illusion kitsunes will have a small leaf icon to the left side of their sprites.
During the first turn, position your troops and enable the attack range of the nearby kitsune groups in your area. Have one of your strongest units to stand within the attack range of the enemy groups to aggro them. You can't do anything with the illusion kitsune near your position so prepare for the next turn to defeat it and heal the injured. Prioritize taking out the skilled kitsunes near your position to prevent them from endangering your riders.
Position someone who can wield the Beast Killer lance, preferably a Paladin or Great Knight like Xander or a reclassed Silas or Peri. The lance can deliver one-hit kills regardless when initiating the attack or counterattacking. Around the fourth turn, the kitsunes with Pass skill will be able to break through your bridge defense then turn into illusions. When that happens, make sure your main attackers surround/block them then either pair your weaker units (healers, spellcasters, Azura) into your stronger units or lead them out of the way. Once the attacking kitsunes have been dealt with, you can now start pushing forward. You can cross the bridge from the southwest or through the makeshift bridge to the north.
Engage the second group of kitsunes in the middle of the map with careful approach. Finally, head towards Kaden. The two Kitsunes with hime have beastbane skillls so be careful not to send your riders/fliers there without proper support or full HP. They have good attack range so it's always a good option to lure them to your position then unleash your army's force on them to finish them off.