Normally, I would try to conceal my powerlevel, but this brings up an interesting point. I remember a hentai called "Sora no Iro, Mizu no Iro" (the color of the sky, the color of the water) and assuming "Iro" is color, then I guess the same rule applies for "One Sky." So I guess it would have to be "Sora no Ichi."
Fuck Japanese classes, hentai is the proper way to learn Japanese.