Toggle Background Color
VIDEO: Watanagashi-hen | TIP 11: From the Scrapbook IV
BGM: Seijaku (Quietness)
The rite of Watanagashi is performed during a village festival every June even now, but reading back to its origin turns up a seriously sanguine ceremony.
Originally, Watanagashi would happen at fixed intervals, and after receiving Oyashiro-sama's trust, they chose a sacrifice. Then, the entire village would kidnap (demon away) the person and ceremonially dissect and devour them in a feast.
(The rules that determined the intervals are shrouded in mystery. This is because the ceremonies occurred extremely irregularly. There's a theory that it was determined based on astrological fortune-telling, but it isn't too convincing.)
Perhaps the act of kidnapping and eating people was done to prove that they were higher up on the food chain.
This is just a hypothesis, but maybe the rite of Watanagashi was a political event for the purpose of being an outlet for (or outright diverting the attention of) the villagers of the isolated Onigafuchi Village, in case any of their complaints or dissatisfactions grew serious.
If that was the main reason these ceremonies were held, then it's easy to explain how erratic they were.