As the Demon King, I had to clean up the mess left after being defeated by my sister who was stronger than the Archangel. As the Demon King was defeated, the balance between humans and demons collapsed, and humans began to brutally enslave the demons. As the former Demon King, I had to save them. However, even though I am a demon king, I have no strong fighting ability at all! This is a story about how a demon king with 0 magic power and full technology tree saves the demon clan.
