Penna/Plot

Plot
When Parona was younger, her village was chosen to sacrifice a girl to the Oniguma. When the bells announcing the Yanome's arrival were sounded, Penna decided to save her younger sister from the possibility of being chosen as a sacrifice by hiding her in the forest under the guise of a game.

After a few days, Parona returns to the village, wondering why her sister never came back. The villagers tell her that Penna isn't there anymore and while not said out loud, it's clear that she disappeared because she was chosen as sacrifice.