At last, the truth is out, and as Rei is taken into custody by the powers that be her friends learn the shocking truth that it was her who played a pivotal role in aiding and abetting the Alone attacks.
But just who, or rather what, is Rei? As normal as she might look, apparently it's more than just the pertness of her buttocks that is out of this world, as Isshiki posits that she's from some kind of parallel world. As the episode continues, so we discover just how instrumental Rei's presence has been to attracting the Alone to attack the planet, leading some parties suggesting that she should be "disposed of" immediately.
Meanwhile, Akane and her friends are trying to come to terms with what they've just learned as they attempt to piece together why Rei would want to do harm to humanity and the Manifestor Engine, and just as importantly swallow the fact that they are now seen as liars by the girl they wanted to be their friend. Ultimately, they simply won't stand for it, so there's only one way to resolve the situation - break into the headquarters where Rei is being held and "rescue" her. This, however, soon proves to be little more than the precursor to an appearance from the being that's really pulling the strings.
As this series has progressed, so it has become more forced in its attempts to espouse friendship over all - it's a rather cheesy sentiment in the first place, and when you continually deploy it so heavy-handedly it doesn't really help. Perhaps the bigger shame here is that this week's installment doesn't do more to delve deeper still into the truth about Rei's back story, instead leveraging it simply as a means to an end that certainly sets us up for a potentially epic and action-packed finale, but without any particularly strong emotional resonance to drive it along.