The MC is barely "otaku". He mentions a pair of times how it sucks to lose a comiket as he is in the fantasy world, jokes like that, but the otaku part of his character doesn't show, in practical terms it just means he is a "laid back" dude. Though of course when the plot wants he isn't laid back at all, don't expect consistent character development lol.
But it will show more in other secondary characters, so there is a ration of otakuness to have: Akibahara shops, fujoshis, doujinshis, otaku fetishes, etc. You can see it has been written by an otaku.