Your campaign has everything it needs to run an adventure based on Princess Mononoke—samurais, monks, gunslingers, dire boars, demons…everything but the head-rattling tree spirits. The kodama kami in the Bestiary 3 take care of that nicely.
Most kodama will be peaceful, if somewhat curious and mocking creatures (again, see Princess Mononoke for role-playing these creatures), but these hooks offer exceptional circumstances that may demand a bit more confrontation…
The forest gnome sage Felix Tinderflame lost his legs to an accident years ago. But his condition has only endeared him to the forest’s kodama, who have fashioned him fine crutches and prosthetics from fallen limbs, and they delight in pushing him around in the wheelchair he designed himself. They can be too protective of him, however, and they mimic, play pranks on—or even attack—anyone heavily armed who seeks an audience with him.
Isolated, hardy trees often have more of a presence than much larger trees safely nestled in a forest. A band of sellswords is told that the spirit of the grizzled, lightning-scarred oak north of the Yellow Prairie River may know more about the ancient barrow mounds that rise up throughout the area. But when they get there, hobgoblins are already consulting with the Large kodama. Even these martial brutes respect the kodama’s age and toughness, but their taboo against harming the kami does not extend to the kami’s guests.
Overlogging is nothing new in many forests. But the mad boy-king Ludeverg sends men to chop down the Deepwood for another reason. He blames the hollow gazes of the forest’s kodama for stealing his innermost thoughts, and he hopes that by chopping down the trees he will kill the mocking kami. Now the desperate kami that remain are sending stags, mandragoras, and even wereboars after any loggers they find in the forest…and they can’t always tell the difference between the blades of a saw and the blades of an adventurer.
—Pathfinder Bestiary 3 162