someone who is delusional or out of touch with reality; a person who seems to be receiving strange signals
Slang term used to describe someone who acts as if they are receiving radio waves, i.e., they have bizarre ideas, talk to themselves, or seem disconnected from reality. Often used in otaku or internet culture.
That person is denpa-kei and always talks to themselves.
You often see denpa-kei posts online.
From 電波 (radio waves) + 系 (type). The term originated in Japanese subcultures, likening a person's erratic behavior to someone who is receiving radio transmissions that others cannot perceive.