Kengo Fukukan, an ordinary middle-aged salaryman, gets caught up in the hero summoning of a group of high school students and is transported to another world. While the high school heroes gain powerful stats, Kengo ends up with only the basic "Language Comprehension" skill—something all locals are born with. Branded useless, he is exiled to the Abyss, a place from which no one has ever returned. While desperately trying to find a way out, he is attacked by massive monsters that dwell in the Abyss, powerless to resist… But this is only the beginning! From the depths of despair begins a journey into an ancient high-tech fantasy world!