Ooh, now this is interesting. There is a strong case for Kasumi being asexual, but aromantic might be a whole other thing and certainly being with Sakurako as much as she is probably fulfills any desire she would have for a partner so she has never had to think about it. Will this move to them at least redefining their relationship, I doubt it, but it would be interesting to see how Kasumi thinks about their current quasi-romantic relationship.
They're finally bringing this up, and it's in a special chapter rather than an actual numbered canonical chapter????
To be fair it is usually the special chapters for this series that contain the drama and introspection with the main series usually just being fluff 4-koma SoL.