Constellation:

Character:

Miyo is a nurse at the village clinic who has a keen interest in Hinamizawa's past and culture, recording all her speculation in notebooks. At times, her storytelling can be very mysterious and chilling—she seems to enjoy putting people on edge. In the first six arcs, she consistently disappears on the night of Watanagashi, and an incinerated body thought to be hers is found in the mountains. Miyo is the person who kills Rika, leaving her body and scattered organs out for the crows to eat. 

Source from Wikipeida