Now that the invaders have come to an understanding of sorts, things are going smoother than ever in room 106. Spring is in the air--tulips, friendships, and potential romances are all about to burst into full bloom. Koutarou and the invading girls have never been happier together, but nothing lasts forever. Things turn dark quickly when they find out that they're going to have to say goodbye to one of their own... and soon. Without even any time to prepare, will the bonds they all share be enough to pull them through?

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 Clan are working their way back home from their interstellar adventure, but they have to make a pit stop about ten years off from their intended destination. As luck would have it, they encounter a young girl right after they land. Worried that she might have seen their spaceship in action, Koutarou decides to dig a little deeper. Things take an unexpected and heart-wrenching turn, however, when he realizes he has more in common with this girl than he initially thought.

With things slowly shifting in their favor, the Reborn Forthorthian Army might finally be able to expose Vandarion for the traitor that he is. When backed into a corner, however, Vandarion reveals just how cruel he can be as his rage, his hatred, and his desperation push him to the brink of sanity. In their toughest fight yet, Koutarou and the girls will have old tricks, their friends, and even their own weapons used against them.

Summer vacation is right around the corner, but can Koutarou and the invaders manage a ceasefire long enough to actually enjoy it? Luck seems to be on their side when Ruth wins them a trip to a seaside hot spring, but it's not all fun and games with shadowy figures stalking their every move. When push comes to shove, can rivals become allies to save one of their own? Or is it every invader for themselves?

Back from his unexpected travels, Koutarou tries to settle into his life as a normal high school student again. A school field trip to a ski resort sounds like just the right thing to do the trick. When they get there, however, Yurika notices that Maki is sneaking into the mountains to use magic. Worried that Darkness Rainbow is up to something, Yurika goes to investigate, but the investigation turns into a lot more than she bargained for when she comes across a demon.

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?