A tengu in 1357 DR had an idea for a great joke: he disguised himself as a dai-oni (or "great oni") and became a leader of some raiders. The idea went well and many sohei and yakuza gathered under the "dai-oni" master of the Black Temple. Soon his followers led raids against nearby villages to gather tribute. The amused tengu led some bizarre rituals in the temple for his followers.
In the end, some adventurers, hired by Sato Masako to stop the raiders, attacked the temple and defeated the tengu and his followers. It wasn't until later when they found the tengu's diary that they discovered it was an elaborate prank.