The term was popularized by William Gibson‘s 1996 novel Idoru, which has several references to otaku.
The otaku, the passionate obsessive, the information age’s embodiment of the connoisseur, more concerned with the accumulation of data than of objects, seems a natural crossover figure in today’s interface of British and Japanese cultures. I see it in the eyes of the Portobello dealers, and in the eyes of the Japanese collectors: a perfectly calm train-spotter frenzy, murderous and sublime. Understanding otaku -hood, I think, is one of the keys to understanding the culture of the web. There is something profoundly post-national about it, extra-geographic. We are all curators, in the post-modern world, whether we want to be or not.^[7]

— Spook Country, April 2001 edition of The Observer

Over five hundred individuals in Japan were polled by the Mobile Marketing Data Labo, providing these insights into how folks can spot otaku:

1. They are using otaku slang, net jargon or 2ch chat
2. They just happen to have anime/manga/game goods about them
3. They respond to otaku type keywords and issues
4. They become very intense when the conversation turns to anime/manga/games, and only then
5. The tunes they hum are all anime related
6. They know excessive amounts about a given anime/manga/game
7. You can somehow just tell intuitively that they are an otaku
8. They talk unconcernedly about anime, manga and games all the time as if it were normal
9. They start talking about a seiyuu (voice actors)
10. They are carrying a bag from an otaku shop like Animate or Tora no Ana