Earth with Dungeon: Koyuu Skill "Touka Koukan Store" wo Kushi Shite Sekai Kyuusai wo Mezashimasu

It has been a few decades or so since dungeons appeared on the earth and demons roamed around the world. However, the era of adventurers as in the stories did not come, and many towns have been abandoned, the economy is in decline, and the world is full of lawless zones that are slowly heading toward extinction. Amano Hobito, who has been training his own skills in the abandoned towns where death is the norm, and Shizuku, a mysterious beautiful girl with whom he shares a common destiny through the "Zanki" skill, challenge to save the world that coexists with dungeons using their unique skill, "Equivalent Exchange Store" as weapons...! (Source: Hifumi Shobo, translated)