Dimensional Cave

次元洞窟（じげんどうくつ） Dimensional Cave d͡ʑiɡ̃ẽ̞n do̞ːkɯᵝt͡sɯᵝ
Screenshot of the cave in Evanescent Existence
Information
Location	Located in an interdimensional space; Currently doesn't exist
Appearances
Evanescent Existence (Main Setting; Original form in Stage 1, altered in all other stages)

The Dimensional Cave (次元洞窟, Jigen dōkutsu) is a mysterious cave located in interdimensional space, formed when the dimensions that the Outside World and Mugenri are located in were connected. The cave is apparently filled with exotic matter, with luminous crystals among countless thick stalactites and stalagmites, as well as a river hidden behind. It is notable that while all the outsiders spirited away by Tsurubami Senri entered through the same entrance, Yabusame Houlen apparently used a different one.

According to JynX, Tsurubami Senri, Tenkai Zuifeng, the characters introduced in Evanescent Existence, and "a few authorized people" are the only people who know about the existence of the Dimensional Cave. However, it only opens up temporarily, so it hasn't existed since after the events of Evanescent Existence. The cave also rarely opens naturally, unless something extremely serious happened. Instead, it is possible to manually force it open, although it is quite difficult.

Spaces

Prior to the events of Evanescent Existence, Tsurubami deployed a special barrier known as the Curtain of Awakening (釁醒帳幕, Kinsei Choubaku) over the part of the cave close to the Mugenri end. Through the curtain and Tsurubami's combined abilities, parts of the cave were transformed into a series of interconnected spaces (空間, Kūkan) via the overflowing power of the outsiders. One space appeared per stage for each occupier (or boss) throughout the game. Tsurubami closed the spaces after the events of the game, sending all the humans still in them into Mugenri, as they did not have the capability to instead send them back to the Outside World.

Spacetime Whirlpool

The Spacetime Whirlpool

Entering the glowing river in the cave leads to the Spacetime Whirlpool (時空の渦, Jikū no Uzu), whose master is Aoji Shitodo and was the result of Aoji's newly awakened ability to create whirlpools. It resembled an ocean from an underwater view, with sunlight shining through the surface and a sandy floor. Many of the stage's enemies also fired danmaku in the shape of a double helix or whirlpool, as Aoji does. The water in the space enabled Aoji to use their ability to create whirlpools of water effectively.

Corridors

A corridor as seen in Stage 3 of Evanescent Existence

Not technically one of the spaces, Stage 3 instead took place in one of the Curtain of Awakening's internal corridors that acted as a shortcut connecting all the spaces together. While it was designed so that only Tsurubami could use it, Yabusame Houlen was able to enter due to their dimension-crossing ability. It was here that Yabusame and Tsurubami first fought each other (although Yabusame thought they were Tsubakura Enraku). Despite the location's exclusivity to Tsurubami and Yabusame, stage enemies still appear here. Suzumi Kuzu was also able to gain access to the corridor via memory access, although with a bit of trouble.

The corridor seen had bright green grid patterns on all four surfaces and which appear to change positions with one another. When entering or leaving the spaces, a square-shaped image of the location may phase in and out of view before disappearing altogether.

Hooaka's Space

Hooaka Shitodo's Space

The space with Hooaka Shitodo as its master contained many peak-shaped rocks and was the result of Hooaka's pre-existing ability to control hot and cold. Its temperature fluctuated greatly from time to time, befitting Hooaka's ability to manipulate hot and cold. The rocks first appear grey when cold, but changed to red when hot. The stage enemies often fired patterns in lined-up formations. If one ascended to a higher altitude, they may proceed into the next space. It is unclear whether the Spacetime Whirlpool would have led to this space.

Kuroji's Space

The Tower that Births and Consumes the Sun

In the air above Hooaka's space, surpassing even the clouds, is the space with Kuroji Shitodo as its master and was the result of their newly awakened ability to reverse front and back. While it's unclear what, if any, special physical features this space has, it was described as a "world that symbolizes turnabouts". The sun can be seen in the sky during this stage, which later hides behind a tower seen in the distance and later re-emerges, turned from bright to black when Kuroji appeared.

Tower that Births and Consumes the Sun

Officially titled the "Tower that Births the Sun, the Tower that Consumes the Sun" (陽を娩む塔餤らう塔, Yō wo Umu Tō Kurau Tō), this space had Clause as its master and was the result of their newly awakened ability to manipulate gravity. From atop the tower, the dark sun leading to Mugenri could be seen in the distant sky. If one flew towards it, they would arrive at the next space.

Despite apparently being Clause's space, it was prominently featured in the previous stage and is seen briefly in the beginning of the next, its title also references Kuroji's ability to reverse front and back. Although it could be assumed that the protagonists fought against Clause in the sky above the top of the tower.

Sun that Casts a Shadow

The Sun that Casts a Shadow

Extremely high in elevation, the "Sun that Casts a Shadow" (影を放つ太陽, Kage wo Hanatsu Taiyō) is the entrance into the Shrine Road and subsequently the Mugenri Barrier and Mugenri. As one ascended to this space from the last, bands of a purple haze could be seen falling down the tower. The sky here was dark with the entrance resembling a solar eclipse and within the sun a torii could be seen.

Shrine Road

Shrine Road

The "Shrine Road" (参道, Sandō) was a long road lined with torii that was submerged under a thin layer of water. It lied just beyond the Sun that Casts a Shadow and leads to the Mugenri Barrier. Unlike the previous spaces, it is unclear whether this is a part of the Dimensional Cave which appearance was warped by Tsurubami's abilities, or simply the way the area around the Mugenri Barrier looked naturally. Seemingly based on the Shrine Road found within Mugenri, JynX stated in an interview that it has a different significance than the one inside Mugenri.

The torii seen along the road are Mitsu Torii (三ツ鳥居, Lit. "triple torii"), famously associated with the Ōmiwa Shrine, where it is known as Miwa Torii (三輪鳥居). They are also known as Sankou Torii (三光鳥居, Lit. "three lights torii") and Komochi Torii (子持ち鳥居, Lit. "torii with children").

The road is the setting of the Extra stage where Tsubakura Enraku met the one behind the incident of the game, Tsurubami Senri, where they spirited various humans to Mugenri. Later, Yabusame Houlen also followed the road, but instead left the path and flew into the Mugenri Barrier instead, where they also met Tsurubami. Both of them defeated the priest, and were made into the Senri Shrine's new temporary priests.

Appearances

Evanescent Existence

In Evanescent Existence, Tsurubami Senri disguised as Tsubakura Enraku first came here in search for outsiders they spirited away, and they came by Kurohebi. In confusion, they both had a duel, and Kurohebi was defeated. After that, Yabusame Houlen came and spotted Kurohebi. At this point they heard that whoever "reaches the deepest area first will have any wish granted", and thus tried to assassinate Yabusame. They were again defeated.

Gallery

• 

  A river shown in the cave

• 

  A bright light appearing before entering the cave

• 

  The ground texture of the cave in Book of the Cafe

• 

  The corridor with a grey background, appearing during the stage's boss.

• 

  Hooaka's Space representing cold.

• 

  The stage before the tower is about to consume the sun.

• 

  The Shrine Road as seen from top-down

• 

  The road again as seen from top-down, but seen further in v1.01a