Current Representative of the Mystery
The rumor begins with an event called “Tsukimachi” where children gather together weaving baskets all night until sunrise.
The children have to stay awake the whole night or their souls will attract The God of Death.
The aspect the Sixth School Mystery oversees in Kamome Academy is currently unknown.
He appears to have a human-like form after removing his mask, with a dark skin tone, short hair, and horns still protruding on either sides of his head.
The boundary of No.6 is under the school. The boundary itself has water as its floor, as all other boundaries do. It seems to be larger than most seen in the series, and contains many traditional-style Japanese buildings connected by a series of bridges; as well as an abundance of flowers. The boundary as well contains a river that No.6 sailed through to bring Akane Aoi to the boundary, to be a sacrifice.
It is shown that No.6 can see anywhere throughout his boundary through some type of crystal ball, which is likely due to the size of the boundary itself.
The boundary as well contains a large hole which leads to pit filled with bugs of varying sizes, as shown by Aoi to Akane, Hanako, and Nene. It is said to be an "exit" of sorts, and those who fall in are never able to exit again.
The hole was later revealed to be the entrance to the Far Shore, where a living being's body will deteriorate until their soul is left behind.
The boundary also contains a grove area. It has no layer of water on the floor, which leads Hanako to believe that it was either made to be like that, or it's a reflection of Sumire's memory. It is inhabited by villagers who initially tried to capture Hanako and Nene. The villagers believed them to be tree stump spirits and pointed out Nene's ankles as evidence. The area contains a house where Sumire resides. Yashiro was tricked into being Sumire and was moved into a palanquin by masked villagers. She was carried to a open pit to be offered as a sacrifice which ended in Sumire offering herself up instead and falling into the pit. This wasn't the end of Sumire however, as it was revealed that the entire area was a prison of time created for Sumire's sake. Whenever she dies, the world's time is turned back to the day before the sacrifice.
The Yorishiro of Mystery No.6 is Sumire.