Hmm, after thinking this for an awhile, I think it should be Miku, why ? Dumb reasons involved, the only one who has the same front hair direction as the bride is Miku. (hair direction involve human behavior in general, it should be hard to imitate, especially when having special ceremony, yes I already see the photo 2 years before the wedding), but that doesn't prove the one who kiss him near the shrine is Miku though..
And somehow between oneshot & real manga only Miku that has different appearance & hairstyle