After Theia receives a distressing message about her mother in Forthorthe, she's forced to make what could be a life-changing choice. Nothing is simple, however, when it comes to the politics of a galactic empire.

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.

Now that Koutarou and company are back from their long journey to Forthorthe, everyone is hoping to settle back down into their normal, peaceful lives. Things are quickly thrown off course, however, when Theia, Ruth, and Clan show up with a little extra baggage and Koutarou suddenly finds himself in the midst of intergalactic negotiations. Has the real alien invasion just now begun? And what’s with the strange voice Sanae keeps hearing? Moreover, what’s got Clan so pensive?

 The Satomi band of knights is steadily expanding and all is well in room 106. At least for a little while. Yurika comes to everyone with an unusually serious request—she wants them to help her savior and mentor, the former Rainbow Nana. Children then mysteriously start going missing in Kisshouharukaze City, which can only mean one thing. The evil magical girls of Darkness Rainbow are back in town and they mean serious business this time. Deadly serious business.

Lately, Koutarou has been growing more and more suspicious of Kiriha. Claiming that she's come to invade the surface is one thing, but what on earth is she doing helping the neighborhood association clean up the city? Is this all part of some nefarious plan? Or is there something else going on? When Koutarou works up the nerve to confront her about it, she responds by... asking him on a date?!

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!

Valentine's Day is right around the corner, and the girls of room 106 are scrambling in preparation for it. It's not all fun and games, however, because not everyone seems to be able to admit their true feelings. Ruth receives a strange message from her parents back home in Forthorthe, leaving her with an important decision to make about her future. And on top of everything else, she seems to be getting closer and closer to figuring out what happened to Koutarou while he was away.