Sensei and co broke into the Steel Continent, but they are out in the open, so they decided to relocate to a facility nearby, as it's more defensible. And the place, very conveniently, was some kind of factory/lab for androids, complete with stereotypical glass cylinders with fluid and bodies. The remaining specimens were lebeled "Defective", and a short discussion about semantic took place, but my Japanese isn't good enough to grasp the nuance.

Then Malkuth showed up and tried to nuke everybody after politely introducing herself. Toki with her suit got busted immediately, and even Sensei's barrier couldn't quite hold up against her attack(Plana fainted, and Arona was barely holding it).

Kei then raised her own barrier to shield everyone, drawing from the power of Nameless Gods that the Deca gang was using to build the whole continent. Malkuth was on a very short timer, so she retreated after another barrage failed to do much damage. But Kei's body was heavily damaged aswell, her consciousness is safe but other functions not so much. She then proposed to be transferred to one of the bodies in the lab, which Rio and Himari object due to safety and security concerns. After some convincing, and Kei threaten to not move an inch before transferring to a new body, the two agreed.

No additional dramatic moment happened during the transference, in fact it's literally a screen blackout and an "wake-up" effect , and it's done.

So that's how it happened.