How to Beat?
First I made one Raider with the building at the starting point. Then I got the crossbow man and send all units beside Kenji to the south just above the tower of the base.
I sent Kenji to the southwest base to kill one enemy then Shinja spawns with his army.
After that I sent Kenji to the tower to the southeast to attack it. While the peasants were busy repairing the tower I sneaked with the army and destroyed the peasent buildings.
Also I tried to be as efficient as possible and build at the same time my village while raiding the base.
That was sufficient to survive and I’d guess I was lucky that the AI did not send reinforcements.
I built a Town square so I was able to build 3 towers with a geisha in them to heal my main army. Then it was a ping pong game. I managed to kill the bigger waves without getting destroyed and somehow I was slowly but steadily destroying the west base. It took a while because the wolf clan did it defend with all might.
After the dragon clan was destroyed it was a walk in the park.
All in all it took nearly 2 hours to complete. And I did retry A LOT. It was so much micro management rubber banding the units because the AI counter combats everything.