The Strongest Tamer Returned from Another World with his Childhood Friend as his Familiar is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

“But I’m powerless without you, my Master.”

After being suddenly summoned to another world and saving that world from a crisis, high school students Wataru and Rumi have safely made it back to the real world. But the real world has been completely transformed! Dungeons are popping up and people have awakened their skills… It’s as if the real world is turning into the world they just left behind…

A dungeon fantasy story where the returnees from another world, the tamer Wataru and his familiar Rumi, mow down everything in their way as the strongest combination that is closer than childhood friends but not quite lovers!