Rainbow Dragon Cave
Rainbow Dragon Cave
The Rainbow Dragon Cave in Unconnected Marketeers
The Rainbow Dragon Cave (虹龍洞 Kouryuudou) is a cavern located on Youkai Mountain. The cave also acts as a mining shaft.
The entrance to the cavern is located on the False Heaven Shelf, guarded by Sannyo Komakusa. The cave gets its name because it contains an abundance of "Dragon Gems", a type of magical ore handed down that acts as a main ingredient for magatama. The cave has a labyrinthine structure, with its full layout still unknown. 
The cave is also an oxygen-deficient environment, which makes traversing the cave dangerous for unprepared humans.
- Unconnected Marketeers
The protagonist encounters Misumaru deep in the mine, where she warns that there is no oxygen further in the cave and that the protagonist should turn around or she will die. When the protagonist ignores this warning, Misumaru fights her. The protagonist wins the spell card battle, but is exhausted by it and finally notices the effects of the low oxygen. Misumaru sells the protagonist a card and advises her to leave the mine and seek the true culprit at the top of the mountain, which she does.
Later in the Extra Stage, the player enters the Rainbow Dragon Cave after acquiring a special Ability Card that allows humans to breath in anoxic environments. After defeating Tsukasa, the heroine gets spotted by Momoyo, with the latter attacking the player after Tsukasa convinces her that Misumaru and the heroine are the thieves mentioned earlier. After getting defeated, Momoyo comments she was pleased to fight someone so strong, and invites the player to a rematch in the future.
- 100th Black Market
The Rainbow Dragon Cave reappears as the location of the 6th Market. Several strong youkai appear here, and Marisa Kirisame notes that she is now able to breathe here like normal, ultimately theorizing that Suika Ibuki used her ability to fill the cave with oxygen so that she could host a party inside of it.
The cave is revisited for the final confrontation with Takane Yamashiro. It is here where Takane, exasperated by the effect of Nitori Kawashiro's Ability Card, willingly gives up control over the black market, believing there is no money to be gained from fighting, only for Marisa Kirisame to challenge her regardless.
Entrance to the Rainbow Dragon Cave in Unconnected Marketeers
The Rainbow Dragon Cave in Unconnected Marketeers (Extra Stage)