裸の王様
An old Danish folktale about a vain and hedonistic emperor who gets fooled into walking around town while "wearing" supposedly invisible clothes that only smart people can see, and his people being reluctant to believe and/or admit the truth until an innocent child points out that the emperor is actually [[completely nude]]. Known in Japan as "Naked Emperor".

The name is sometimes used idiomatically to describe the phenomenon of "pluralistic ignorance":[https://en.wikipedia.org/wiki/Pluralistic_ignorance].

Apply this tag when the character alludes their state of nudity to the folklore (such as referring their cloth as the one that only X could see, etc.), or depicts the scene of the original tale.
emperor's new clothes