Talk:Sanae Mizuno/@comment-65.34.106.12-20140116043939/@comment-397235-20140709002456

She very blatantly flirts with him in one of the inserts for the manga. Kouichi gets irritated with her for taking a long time to explain things and starts rambling about the kinds of men she likes, and she rather coyly asks if he's jealous. Kouichi indignantly replies that he's not, to which Sanae rather creepily asks if he's ever even thought about it (ew, any way you slice that), before finishing it with "Maybe in five years..."

I always saw her as treating Kouichi like a surrogate younger brother, since she and her own brother weren't especially close. At least that's how it comes across in the anime (in the film they don't really have any kind of relationship at all). That's the sanitized version, anyway. I can see it; my sister and I aren't especially close, but my cousin, who's a little closer to me, is basically my surrogate sister.