Uno x Uno
30/10/2014 Update
From Hachimitsu Scans:
Despite Mai and Yuu Shindou being fraternal twins and opposite sexes, they look very similar to each other and are surrounded by people who want them to act more like twins, such as wearing matching outfits or clinging more to each other. Amid this, Mai starts to realize that both of them are starting to change as they start going through puberty.