Meaning of “layer(レイヤー)”

“Layer(レイヤー)” is an an abstraction for “cosplayer(コスプレイヤー)” as a slang.

Some Japanese love costume playing. Even me, I have some friends who loves it.
However, it’s not so common hobby in Japan, except for on Halloween.
For Japanese, Halloween is a pumpkin desserts day and a cosplayer day in my opinion.
Especially in Shibuya, you can see many crazy cosplayers.

Example Conversation

A: Is she a layer(レイヤー)?
B: Yeah, I’ve heard, she do costume playing in Comiket.

A: あの子ってレイヤーなの？
B: あー、なんかコミケでコスプレしてるらしいね

*Comiket is a biggest fanzine event.