What's a rainbow?

In this world everyone can only see black and white. At least until you turn 18. On your eighteenth birthday you can see the color of your soulmate's eyes. As you get closer to figuring out who your soulmate is, more colors will appear as clues. Then finally, once you figure out who your soulmate is, you can see all color.

Langa has been 18 for a while, and he finds it curious that the only color he sees is the exact color of his best friend's eyes. He's been counting down the days until Reki's birthday, praying Reki will see blue.