So after reading this chapter (14) I'm convinced that Kotooka is takoyaki boy.
I mean, she's REALLY girly, like super girly. It wouldn't be that far a stretch that the reason she is as girly as she is is because she used to be very tomboyish, like even when they first met her hair was short. So I'm thinking that junior high was when she made the decision to change herself (as most of them did) and become more normal.
Not only that but she even said she wanted to finally be "normal", that could be interpreted a few ways. But after seeing that and then the fact that takoyaki boy had blonde hair, I leaning more towards Kotooka.
Still keen on Washio x Tsukasa tho