I never implied whether she wanted Hisao or not. Simply implied that since she was pretty much conditioned into a life where the only person who cared about her was a blue haired deaf girl, she probably "fell in love" with her.
Really though, it felt more like a sisterly "love", or a really close friends "love". The kind of relationship you share with someone who you can tell the whole world to, but not someone you'd mess with in that sense.
Since we're here, we probably don't have someone like that, but it's common for people to have someone like this, especially when they're older and have withstood the storm, or whatever that saying was.
Misha's "Problem" was an entire childhood in solitude as Shizune's route had suggested, and as she had suggested. She was a "loner child" and her way of acting is only like so because she puts on a mask to hide her real problems and feelings; the mask breaks away in Shizune's route, but in the end, it still seemed like it was there.
Due to this problem of hers, when she found someone who would be that super close friend, she mistook it for feelings of love and attraction. It's not like it only happens to girls, it happens to guys too. It's how manipulation takes place, but the manipulator isn't always aware of what they're doing, similar to this case.
Shizune doesn't want to manipulate Misha; if she realized she was doing it, she would probably feel terrible, but wouldn't want their close friendship to change, which is more than understandable. Misha, also understandably, wouldn't want their friendship to change were she to realize the consequences of it changing.
TL DR: If you close the world to someone and then show them the best part of it, you can twist them around your fingers easier than a piece of string. However, in the case of this manipulator (Shizune), she had accidentally walked into Misha's closed world and showed her a beautiful part of the real world, and Misha mistook it for the whole world.