Hacker News Reader

it's pretty well known/used in english online communities, yes. especially if you go anywhere near anime.

Not to me, and I've been involved in online english communities since the late 90s.

I have heard otaku though.

It was a pretty popular subject on HN as recently as a few years ago. I dont know very much Japanese, but I am familiar with that one due to the other articles that explore the culture. I suspect that there's also some bias at play: the people who are commenting are ones who are already familiar with the term.

Especially online communities about computers.

https://en.wikipedia.org/wiki/Welcome_to_the_N.H.K.

If you like anime dubs, especially the ones with the same two guys who voice the protagonists of _every_ Funimation dub, they're in the dub of NHK and it's pretty funny.

はい。