Well, readers of the light novel already know how it turns out. And you're right about Akane's not being recognized by Saito being a REALLY stupid reason for her bitchiness. What did she expect: She never told Saito her name, and it's been at least four or five years since he last saw her, in which time she grew from a literal kid into a curvy young woman who looks nothing like she used to. Even someone with Saito's memory would realistically be at a loss. Puberty can radically change a person's appearance, regardless if that person is male or female.