The Buddhists Monks were a minor group of villains that appears in the visual novel and anime of AIR.
Kannabi No Mikoto's Curse
When the monks discovered that Kannabi No Mikoto wasn't guarding the temple and left to see her mother, they put a curse on her which also extended to her reincarnations. The curse was that she would die if she ever fell in love. Kannabi was later killed by the soldiers that invaded the temple. The monks are also responsible for Misuzu's death since she was a reincarnation of Kannabi. After the heinous acts they did, they got off scot-free.