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. Later, however, it turns out that she is the mastermind of the events taking place in Hinamizawa who wants to murder Rika so she can prove her grandfather's research. Since her will and manipulations are so strong as to affect the people in the village both directly and indirectly, she infact fakes her death through the first six arcs of the story (the corpse in the barrel being a stolen corpse), and murders Rika in three of the arcs which she uses in line with her "Queen Carrier" theory to execute the Great Hinamizawa Disaster.
