While the magical girls of the Corona House crew are out on patrol one evening, they’re treated to a most unusual sight—a Sanae they don’t know falling from the sky! Just who is this third Sanae, and what is her story? Koutarou and the girls have kept Earth, Forthorthe, and Folsaria safe thus far by driving back evil after evil... But the threat lurking in the shadows now is unlike anything they’ve ever faced before. Will they still be able to defend themselves and everything they hold dear when the stakes of the battle they’ve been fighting shift significantly?

Harumi and Clan take a sentimental tour of Vandarion’s special territory, swapping secrets (and more!) in hopes of better understanding their respective relationships with Koutarou. Theia and Ruth also take a trip down memory lane as they review footage and data from their trip to Earth. Shizuka and Sanae likewise reminisce about the past while doing some spring cleaning. But then it’s time to kick back and cut loose! The whole gang heads to the beach, where the girls get their chance to shine bright!

Koutarou has sunk into despair. He was given the agonizing choice of saving either Fasta or Ralgwin, with the other losing their life. As a result, Maxfern was resurrected, leaving Koutarou at a loss and full of fears. What will be the catalyst for his recovery? The girls of room 106 struggle to reach out to him, but it’s an unexpected friend who pulls Koutarou back from the edge. Once out of his slump, he resolves to take action against Maxfern. In order to find any leads on their enemy, Koutarou, along with Maki and Nana, infiltrates an enemy organization!

The evil magical girls are finally making their move to seize the mana pool in room 106, just like Yurika's been saying all along! Koutarou crosses paths with an old enemy, and Maki is forced to decide whether she follows her duty or her heart.

Just starting high school, Koutarou is moving out on his own to take some of the burden off of his widower father. Lucky for him, he's found a room at Corona House. It has a great landlord, it's not too far from school, and best of all, it's dirt cheap. It really is perfect... except for the strange girls that keep appearing to try and take it over! But even as room 106 turns into a battlefield, Koutarou isn't willing to give up his apartment without a good fight. The invasion begins!

Koutarou and the girls prepare to chase Ralgwin back to Forthorthe, but one critical mission remains before they can leave Earth behind again—they must oversee the welcome ceremony for the next wave of intergalactic transfer students. Little do they know that someone is watching their every move from the shadows, someone with a keen interest in both Koutarou’s sword and Nalfa... Indeed, the Gray Knight is getting dangerously close the group and the truth about what happened back in the ruins. Will their rematch with him be their final showdown?

Growing up in rural Chichibu, Mari Okada wanted nothing more than to leave her truant lifestyle behind to live in "the world outside." This screenwriter faces her own anxiety as she embraces her past through the words she screams on the page.