Not Gate

I saw an anime ages ago where a gate or something appeared & an otaku soldier gets picked as the ambassador bc his otaku experience was conducive to the mission. I remember a scene in in episode 1 or 2 where he wakes up in a mansion & a bunch of different girls are essentially treating him like royalty. I don’t remember why but I think it was bc of everything that Japan was sharing with them. I thought it was Gate until I finally watched it & realized they were definitely different anime. Does anyone know what anime it is? I think I watched the episodes I saw on Funimation (before the merger)