The Devil Is a Part-Timer!, Vol. 16 (light novel)

This is the story of when the Maou the MgRonald employee was still Maou theDemon Lord! Right as Alciel brings more allies into the fold of the newly formedDemon Lord army, Lucifer rises up in revolt! Fed up with the way he's beentreated, the the upstart rebel obliterates Maou's fortress and flies off,starting a wild goose chase that leads Maou and his comrades to the treacheroussouth!