If you're looking for manga similar to Gate 7, you might like these titles. All recommendations are made by Anime-Planet users like you!
Both series are about a seemingly ordinary guy who gets drawn into an underground conflict between supernatural beings. Individual battles take place in a sort of pocket dimension which outsiders can't access, but the protagonist in each series somehow gets drawn into them despite this. There are also hints that the protagonist in each series has some super special powers, but none of the characters can figure out exactly what those abilities might be.