Having dealt with the threat of rogue classmate Yuuki Tachibana, Yogiri and Tomochika find that things are only getting worse. Their previous adventures have drawn the attention of the Sage Lain, and it didn't take long for her subordinates to track them to Hanabusa, where they had intended to reunite with the rest of their class. Between the Sage's minions and the arrival of a new Aggressor, it seems their luxurious stay in the city is coming to an abrupt end. As the landscape around them is transformed into a post-apocalyptic nightmare, the two are forced to realize that reuniting with their class may be a lot more difficult than they had first imagined...