With Forthorthe on the verge of erupting into civil war like it hasn’t seen for thousands of years, Elfaria and the others do what they can to regain the trust of the citizens. But as it turns out, all of Forthorthe has their eyes on her, her daughter... and the mysterious knight in blue armor. Can they win the hearts of the people while trying to keep a very big secret from them? And with the vicious Vandarion plotting against them, it looks their bloodiest battle yet may be looming on the horizon.

It turns out the timid, polite Harumi has a secret admiration for the way Kiriha teases Koutarou, so she does the unthinkable—she asks Kiriha to teach her how to become a bad girl too! In the next story, Clan also asks for something a little unusual. She starts martial arts training under Koutarou and Shizuka, but is she really up to the task when she can barely handle her own feelings? Next, there’s a surprise royal visitor to room 106, and Sanae, Yurika, and Maki decide it’s time for a makeover of magical proportions. Finally, it’s time for the Kisshouharukaze school field trip, complete with surprise confession!

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!

After getting back from Forthorthe, everyone was hoping they could spend their days in peace for a change. But as if the politics of the official Forthorthian invasion weren’t enough, something very strange and very unsettling is starting to happen around Koutarou and the girls. One mysterious disappearance becomes two, and there’s no clear cause or end in sight. Can they figure out what’s going on in time, or will Koutarou end up just like he was in the beginning—alone?

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?

With the coup d’etat back home in Forthorthe finally reaching critical mass, Elfaria and Theia decide it’s time for them to return. Theia is reluctant to drag her friends into the politics of her homeland, but they’re just as stubborn as she is. They band together and set out for Forthorthe, but their enemies will make sure not even the trip there is easy. They all have a long, hard fight ahead of them—and this is just the beginning.

Volume 20 is a special collection of side stories. First up, Yurika announces that she’s quitting cosplay—or, at least, that’s the impression the cosclub gets. Next, Sanae and Ruth do a little dream diving. After that, Maki confronts Theia about some unexplained expenses she’s recording in the Satomi knights’ ledger. Then lastly, Shizuka recruits the entire Corona House crew to help out with the cook-off at the cultural festival. The girls will cook while Koutarou judges, and the results are explosive to say the least.