Probably not, the author only makes Mafuyu excited with girls to accentuate the fact that Mafuyu doesn’t really know how to be a “normal girly girl”. She has only really grown up and been around with delinquent males (even now), so the author designed her to seem more “manly” and “boyish” as a result of this. Mafuyu’s environment and experience makes her act more like a “boy” and therefore allows her to be excited like a “boy” when around girls (also because girls are foreign to her as established in the early stages of the manga). In general, the author has never really made any other relationships other than hetero ones when you look at all her mangas. So I doubt the author made Mafuyu bi.
I see. Thank you for replying and explaining.
Is mafuyu bi-sexual? She often gets excited with girls so I am asking.