The Brave Men All Want to Practice Asceticism With the Devil King

The cold-blooded Demon King who has beaten all his enemies, who has always been second to none, ended up losing all his magical powers to a female hero who hexed him. What is this magical ritual that you do with the opposite sex’s lips? I can’t believe that even I, the formidable Demon King, have been defeated by this mysterious move! But no worries, I can retrain my abilities. It doesn't matter if you’re a succubus, an elf, a beast woman, or a noble hero’s descendant. I’ll use you as my training partner if I can help it. In order to revive the demon race, I’ll show you the Dual Cultivation Method!