Oitekebori no Renkinjutsushi

The heroes, summoned to a different world by the goddess to defeat the Demon Lord, returned home after sacrificing much. However, the alchemist Koudou, who was supposed to return with them, was left behind in the other world because he was in the midst of alchemical concoctions when the goddess's power repelled him during the summoning. How will he survive in this abandoned fantasy world? The production fantasy manga begins!