Kunitsu-Gami: Path of the Goddess

It seems this is one the toughest boss fights in the game, and it's only boss 3. The way I finally defeated was by doing the following:

1) Upgrade the Woodcutters all the way (you'll have to do most of the bonus objectives in the regular stages and repairs in your bases to get enough musubi to upgrade). Use any leftover musubi for the Ascetic.

2) I set my Tsuba Guard ( ability) to Rikugo's Vigor (the one that speeds up your villagers and increases attack power).

3) When preparing for the boss fight, select four Woodcutters and one Ascetic.

4) Before the fights starts, I placed each villager near a lantern as best I could.

5) One thing to note is that the boss will never attack the Yoshiro if you are not near her.

6) Light all the lanterns, and for the lanterns without a villager next to it, choose one and have that one villager light the rest of the lanterns.

7) When the room is lit, set your command mode to Attack, then use your ability and just wail on the boss.

8) When the room goes dark, set command to Defend. Then, one lantern at a time, choose one of your Woodcutters to light a lantern. Once he lights one, immediately have him light the next one. Go in a circle using this process. I tried to start with one of the lanterns near Yoshiro and then go around the room. When you get to the last one (which should be the other lantern next to Yoshiro), you can use a different Woodcutter if you want.

9) Repeat steps 7-8 and remember to stay away from Yoshiro.

I was able to do defeat the boss with this method on my first try without any damage to Yoshiro. Good luck, and I hope this helps anyone who is struggling!