The once-feared Demon Lord Satan of Ente Isla, who had to flee to Earth after being defeated by the hero Emilia Justinia, is now leading a peaceful life in Tokyo under the alias Sadao Maou. Amidst a violent argument between Sadao and Emi, a dimensional portal suddenly appears, carrying a mysterious apple that harbors a toddler named Alas Ramus. To everyone's bewilderment, she imprints on Emi and Sadao, marking them as her parents! After Emi reluctantly agrees to help Sadao take care of Alas Ramus, their semblance of normal life is jeopardized by the appearance of the archangel Gabriel, who comes bearing bad news. He claims that he must take both Alas Ramus and Emi's sacred sword with him—lest the world be destroyed. Unable to accept Gabriel's grim prophecies, the hero and the former Demon Lord need to put their differences aside and unite to protect what they hold dearest.
Maou and company face their usual budget crisis while Emi and Suzuno attempt to have a conversation next door. It's the same old, same old... except that today, they sense an ominous presence. Before long, a bloodcurdling scream will rend the night.
Alas Ramus seems dead set on the idea that Maou and Emi are her parents. After a few attempts at babysitting by Maou and Ashiya, though, it's clear that Chiho is the only one ready to cope with the realities of parenting. Her boss at MgRonald's isn't thrilled about all of this, but Chiho may have a future in the Devil's army.
Maou, Emi, and Alas Ramus have an eventful day at the amusement park. Meanwhile, their three stalkers do their not-so-great best to blend in.
Emi attends a sleepover at the Devil's Castle. But in the morning, the fight for Alas Ramus and the sacred sword begins. Will Maou and Emi win? Will Gabriel take what's precious? Will there be a magical girl transformation sequence?!
Alas Ramus may be safe, but Maou and his roommates have a few more crises to face. Luckily, they have strong allies on their side.
With Ohguro's new and improved look, business is booming! In fact, there are more customers than Maou and his team can handle alone. And at night, there are ominous shadows in the fog...
Emi, Maou, and the gang learn the source of the recent demon invasion, as well as some surprising facts about Choshi City and their boss.
Maou, Ashiya, and Urushihara get a farming job on Chiho's recommendation. Emi seems to have some feelings about it.
Thieves and demons and bears, oh my!
Maou thirsts for a TV, Emi learns some shocking news, and Urushihara schools us all on how to be proper NEETs.
Buying the Devil's TV is more exciting than anyone expected. Unrelatedly, Maou is wiser about human relationships than anyone expected.
The whole gang prepares for their showdown with Raguel. But the fight has a lot of unexpected twists and turns, thanks to meddling from more than one immortal.
The Sasazuka MgRonald's remodeling is complete. New toilets! Better coffee machines! Maou and Ashiya's worries would be over, if it weren't for the girls' suspicious new habit.
The battle with Gabriel and Raguel is over, but the transition back into daily life isn't all smooth sailing.
Maou has been thinking about dreams ever since his conversation with Kisaki, and he knows exactly what to do next. Of course, whether he can get the necessary parties' buy-in on his dream is another matter...
Alas Ramus deserves a safe and comfy place to sleep! Emi and Maou go on a futon-shopping quest while Ashiya and Urushihara try to figure out what's going on with Suzuno.
Emi takes a trip to Ente Isla. Those left behind in Japan spend a lot of time arguing about whether or not they're worried.
Urushihara and Suzuno rush to Chiho's aid, but Maou lags behind thanks to his lack of magic and his confusing new acquaintances. Meanwhile, Ashiya has the toughest job of all: explaining all this to Rika.
Who's holding Emi hostage? Why are so many humans, demons, and angels after Ashiya? Maou needs to find out all this and more, but first he needs a new source of power to defeat the invading army with.
Emi is freshly struck by all the differences between Ente Isla and Japan. Then Alas Ramus reveals more about herself, causing Emi to reevaluate several things. Meanwhile, Maou is just trying to coexist with Acieth Alla without losing his mind.
Maou and Suzuno make their way through Ente Isla's forests. Emi and Ashiya each learn what they've been brought to Efzahan for.
Are we about to finally learn the landlady's secret?! Also, Ashiya takes control of the Malebranche while Maou struggles with his magic and Emi struggles with the stress of her position.
Suzuno and Albert's plan hits a snag, but Emi and Ashiya's plans are going oddly well. The big questions of the day are: Can Maou merge with Acieth again? And does he have enough gas left in Powered Dullahan III?
At last, all the players are in place for the final battle in Efzahan. What happens next?