Denpa song

The Japanese term denpa (電波, "electromagnetic waves") originally arose in the 1990s to describe quirky individuals who often daydream and live in their personal fantasies, and was derived from the Fukagawa Street murders [ja] in 1981.

The assailant, Kawamata Gunji (川俣軍司), was using illicit substances when he slashed random bystanders in broad daylight, killing two housewives and two toddlers and injuring many others.

Examples of such usage at the time include songs by Japanese metal band Kinniku Shōjo Tai, which made references to the murder incident.

Eventually, the term denpa began to encompass anyone who seemed quirky or out of tune with reality, as if these people were being hypnotized or controlled by electromagnetic waves.

Denpa songs often feature repetitive chants or off-key singing alongside a catchy melody, accentuating the excessive energy of the music.

Denpa was, in its early days, associated mainly with creepy music, and as a result, became frowned upon in the mainstream and remained confined to niche otaku groups.