Potion Koujou ni Sasen Sareta Ore Renkinjutsushi, Bishoujo ni Rachisare Ikoku de Itsunomanika Eiyuu ni naru

Demoted from a Royal Magician, Yulius leads a hopeless life in a potion factory. He's kidnapped by elf sisters into a desert country, Shambala, where he creates an experimental potion to rescue the Beauties. He switches from a genius Magician to a strong hero.