A camera invented by Dr. Kunihiko Aso, a researcher of the other world, that can capture images of "impossible things".
The camera was brought to Minakami Village by Seijiro Makabe when he visited it, lent to him by his friend Dr. Aso so that he could photograph a location there that must not be seen.
It also possesses the power to capture images of residual thoughts lingering in a given spot or seal away attacking vengeful spirits by taking photographs of them. It is equipped with four types of filters - "Capture", "Exposure", "Paraceptual" and "Radiant" - but these incomplete functions have been sealed away, deemed to potentially pose a risk to the user.
After acquiring the Camera Obscura, Mio gradually unlocks each of its functions.
One of Dr. Aso's earliest successful inventions during the course of his other world research, this device is used to pick up voices from the spirit world.
Its formal name is "crystal-type other world radio wave receiver".
Its mechanism is quite similar to that of a crystal radio, detecting radio waves by placing special thought-filled crystals known as spirit stones into a panel on its front, allowing one to replay residual thoughts of the dead, fragments of past conversations and so on in audio form.
Dr. Aso lent it, along with the Camera Obscura, to Seijiro Makabe for his visit to Minakami Village.
A small settlement previously located in a certain area of Japan, in a region formerly known as "Minakami".
It is also known as the "Lost Village", owing to the fact that, along with every last one of its inhabitants, it vanished without a trace on the night of a festival.
Deep beneath Minakami Village lies the "Hellish Abyss", a pit linked to the underworld. For generations, the villagers held a secret festival called the "Crimson Sacrifice Ritual" in order to pacify it, but the ritual's failure caused the village to be swallowed up by the darkness of the "Repentance", disappearing from the land of the living. Even now, persistent rumours claim that any who venture into the nearby forest will wander into Minakami Village and become trapped there.
A secret place in the mountains where sisters Mayu and Mio Amakura used to play together all the time as children.
It is close to the place where the sisters were born and raised. When they were little, they would go there with their mother Shizu, and once they got a little older, they would secretly visit to play together. Deeper within the forest nearby this stream is a wide open area filled with grass, where the two used to sleep together.
Mayu suffered the fall that caused her leg injury while she was on her way home from this stream, meaning that not all of the sisters' memories of the place are happy ones.
It has been decided that the area will soon be flooded, lying beneath the reservoir created by the construction of a dam.
A secret festival passed down in Minakami Village since ancient times.
This festival is performed to pacify the "Hellish Abyss", a great pit connected to the underworld that lies far below the village, in order to protect the village from the "Repentance", in which the darkness of death erupts from within.
Twin sisters (or brothers) born in the village serve as sacrifices in the ritual. When a pair of twins "become one", a butterfly is born and flutters away, soothing and subduing the abyss.
In Minakami Village, it is taboo to witness this festival, and accordingly it is known as "the festival that must not be seen".
Each person present during the ritual is blindfolded, meaning that only the twins who serve as shrine maidens (acolytes) know precisely what it entails.
The existence of the festival reached the ears of Seijiro Makabe by way of Ryozo Munakata, who heard of it from Itsuki Tachibana.
These entities are born when twins "become one" in the Crimson Sacrifice Ritual. Lingering afterwards as guardian deities, they continuously flit about the Hellish Abyss and village.
Feared by the villagers, they are also an object of worship.
It is believed that in order for a butterfly to be born, the Twin Shrine Maidens (Twin Acolytes) must act without hesitation or fear, and should the ritual fail, the offered sacrifice is unable to become a butterfly. It is also said that some crimson butterflies were born from intense emotions, but the veracity of this claim is unclear.
Twin girls who play a critical role in the Crimson Sacrifice Ritual. Boys are known as "Twin Acolytes".
In Minakami Village, it has been claimed since ancient times that twins were originally a single entity born divided, and that they possess a special power.
It is believed that in reverting to their original form and becoming one, twins have the power to subdue the darkness of death.
Each pair of twins born in Minakami Village shoulder the destiny of becoming shrine maidens (acolytes), and are not permitted to run from their duty.
Refers to the half of a pair of twins who, having fulfilled their duty as a Twin Shrine Maiden in the Crimson Sacrifice Ritual, remains in the world of the living. As well as being revered for having made a sacrifice to protect the village, people also steer clear of them, believing they must not become involved with one who has contravened village taboo.
More than a few of their number become emotionally closed off, lose their minds, or take their own lives, unable to bear the weight of having taken their sister's (brother's) life with their own two hands any longer.
The Old Tree contains the graves of the Remaining, their souls consoled by endlessly spinning pinwheels.
One of the festivals passed down in Minakami Village. A substitute for the Crimson Sacrifice Ritual, it is held in its place when there are no twins within the village, or when they have not yet undergone preparations to become shrine maidens.
Just as the Crimson Sacrifice Ritual, its purpose is to subdue the Hellish Abyss by offering it a sacrifice, but its effect is only temporary.
Serving as these human sacrifices are "Outsiders" who arrive in the village as visitors, and, after receiving a warm and courteous welcome, are slashed to ribbons from head to toe whilst still alive, then thrown into the Hellish Abyss as a "kusabi".
Living sacrifices that are offered to the Hellish Abyss as part of the Shadow Ritual. Unlike the Twin Shrine Maidens of the Crimson Sacrifice Ritual, people from outside of the village are selected as kusabi.
Those brought into the village in order to become kusabi are known as "Outsiders". After being welcomed into the village, they undergo the Cutting Ritual, in which their bodies are carved up while they are still alive.
The more intense the pain inflicted upon them during this process, the more potent of a kusabi they are believed to make, allowing them to seal the abyss for longer. Part of the bodies of those who become kusabi is enshrined within the Umbral Mound, deep within Minakami Cemetery.
A forbidden place that lies deep beneath Minakami Village. This enormous pit is said to lead to the "underworld", the realm of the dead, and is feared by the villagers who believe it is a place that must not be seen.
Those who peer into the depths of the abyss have their sight stolen away, some even losing their minds. Even merely speaking or writing its name is considered taboo amongst the villagers.
The reason why sacrifices are made and the Crimson Sacrifice Ritual and Shadow Ritual are continuously performed is to seal away the darkness of death erupting from within the abyss from time to time, protecting the realm of the living from calamity.
The disaster in which the darkness of death erupts from the Hellish Abyss that leads to the underworld, causing the boundary between life and death to disappear and the two realms to become joined. This calamity is the greatest taboo in all of Minakami Village.
In order to avoid the Repentance, the Crimson Sacrifice Ritual and Shadow Ritual were performed in the village generation after generation. However, due to the failure of the Crimson Sacrifice Ritual in which Yae and Sae Kurosawa served as the Twin Shrine Maidens, this taboo was finally broken.
Though the darkness that overflowed from the Hellish Abyss swallowed Minakami Village in one big gulp, it was sealed away by layer upon layer of barriers that had been erected, erasing the village from the realm of the living.
These barriers have begun to come apart at the seams over time, and these days, people occasionally find themselves wandering into the village.