I really like the angle that Sanae is an anime fan when she was still outside. Like, if we take this Gundam example, I can totally imagine her in a bidding war for outside world items that includes a blu-ray for the latest movie.

Or hell, maybe she asks Yukari (and by proxy, Ran) to get one for her, but they would more often than not get it wrong – so she would usually ask Sumireko instead.