일코

It is a person who likes something so much that they might appear strange, but tries to appear like an ordinary person to those around them.

JjangjoshL6

어떠한 것을 매우 좋아하여 이상한 사람처럼 보일 수 있는 사람이 주변인에게는 평범한 일반인처럼 보이려는 것이다.

"Passing as a normal person," shortened — hiding your fandom or niche interest from people who don't share it.