What the Yellow Key definitely does
It is one of three coloured keys — red, blue and yellow — and the three together open the gate to the Nushi’s Lair, which is how Chapter 1 continues. That much is not in dispute anywhere: the guide making the contested claim states it, the guide that does not make the claim states it, and no player in the thread argues with it. Leafuly adds the wrinkle that the Yellow Key is itself obtained using the Tailwater Key, which is why players arrive at it expecting a further use.
The claim, and who makes it
NerdsChalk’s Yellow Key guide, bylined Priya Singh and marked updated 4 August 2026, says the key "also opens an optional locked building north of the river", and that "inside is one of the area's Strongboxes containing valuable loot". No coordinates, no landmark, no screenshot and no map reference accompany it. That is the entire published basis for the door, and it is one sentence.
What the players who went looking found
Four replies in the Steam thread, over about eleven hours, none of them contradicted by anyone in the thread:
- Patton: "As far as I know there is no extra door for yellow key."
- Leafuly: the key "is never used for anything outside of unlocking the boss door".
- Laughing kookaburra: "i ran through the map 3 -4 times, im pretty sure there is no yellow key door".
- Santa: names the NerdsChalk article as the origin of the mistake, and notes it keeps reaching people through search.
A second forum, six days later, reached the same answer
This page was written from a Steam thread. On 2026-08-11 the same question surfaced independently on r/BeastofReincarnation — a player who had found the optional Red and Blue doors and could not find a Yellow one — and it played out identically: two replies said there is no yellow door and that they had never seen one mentioned anywhere, and the asker then posted the NerdsChalk sentence himself as the reason he had gone looking. That is the same single sentence, named as the origin by a second set of players who had never seen the Steam thread. Two forums, nine days apart, converging on "one guide says it and nobody can find it" does not prove the door is absent — but it does retire the possibility that the Steam thread was one unlucky group who missed it.
Why this stops short of "the guide is wrong"
Four players failing to find a door is strong, and it is still absence of evidence. None of them is a developer, none published a map sweep anyone can check, and we have not cleared the game ourselves — this site has no interactive map for exactly that reason. What can be said precisely is the asymmetry: one source asserts the door with no locating detail, one independent guide covers the same three keys and never mentions it, one mega-site could not be checked because it blocks us, and four players who looked report nothing. If you are hunting, the honest advice is to stop; if you find it, we would rather publish your screenshot than our reasoning.