I am not sure who made up this term, but I think this is well put, and I really want to appreciate it. Yes, normally it should be written as 一般人[ippanjin] which means “general” people. But actually this kanji 逸[itsu] stands for deviation. Techinically it could be said like 逸脱[itsudatsu]. So the first kanji shall be replaced by 逸, this term was made up…See what I mean? If non-otaku folks are 一般人, otaku folks are 逸般人. 逸般人 means those who live outside the general society…literally. And then those 逸般人 can say those who live outside otaku circles are 一般人. I guess some otaku people might find this so insulting, but personally I like this term. Yes, I am a 逸般人.^^
Also, how can a 逸般人 be a 一般人? Yes, there’s one appropriate term to answer it. That’s 社会復帰[shakai hukki]. It simply means rehabilitation, to return to the society. But actually, in 逸般人 circles, 社会復帰 means to stop being a otaku in order to be a 一般人(general person). Again, some otaku people might find it insulting…because all the otaku people are not those who really need to rehabilitate
such as Sato-kun in Welcome to NHK! in the first place. If you don’t want to say 社会復帰, you can also say like カタギになる[katagi ni naru, “to stop being a yakuza to be a general person”] or 足を洗う[ashi wo arau,”wash one’s feet”] to mean to be a 一般人. Both stem from yakuza terminology, but are already common among general people.
Having said that, in 逸般人(or doujin) circles, they seem to say like 一般禁[ippankin] to keep such 一般人 out of their circles. 禁[kin] stands for forbiddance. It could be said like パンピ禁[pampi-kin] or P禁[p-kin]. パンピ is a more casual form of 一般人, and P stands for “p” of パンピ[“p“ampi]. Some real 一般人 would say like otaku people often draw a line to quarantine themselves by using such a word, but personally I don’t think so.
Well, mostly 一般禁 can be labeled on a fan-made comic(同人誌), especially BL manga. In such a big otaku event(like Comic Market), some 一般人 would join. So in order to warn this kind of thing contains something 一般人 dislike, it is supposed to be labeled. Or else, it is used to inform that you don’t understand what this fan-made comic talks about unless you know the original of it so well. So that’s why I think 一般禁 is not used to keep 一般人 out…What if a 一般人 picked up a BL manga not knowing what it is? Neither 一般人 nor 逸般人 feel good…At any rate, they just implore those who are not intersted(or dislike) in their genre not to take it by using 一般禁.
I am hoping both of the two societies could mutually esteem more than ever and have fun. (´・ω・｀)