I'm assuming Human Order here just means "plot contrivance".
(Yes I realize in-game it has something to do with human history and civilization imposing some sort of collective unconscious will on the natural order of things... and looping back to history or alternate timelines or something somewhat, but reading Nasu's more recent tortuously labyrinthine complicated-for-the-sake-of-being-complicated plots for any significant period of time juuuust makes me wanna slit my wrists, so... JUST TURN OFF BRAIN AND ASSUME MAGIC PLOT CONTRIVANCE!)
Updated
Why did Rice-san, whom you supposedly have never met before...
...I just didn't have the heart to stick her on the frontlines, you know? But my room is filled full too... okay?
...address you as "Onee-sama"?
Maa-chan!? T-That girl! Don't tell me...
Which is why... could I leave her here for now until something or whatever happens with the Human Order, please?Ah!...I hate perceptive kouhais like you.
...she's Rice Shower-chan!?
Figured a fellow comrade would be enthused with this...