Min Yoongi, also known as Suga, lives in a world where if someone likes you, your nails are coated in the colour of their eyes, and is impossible to remove unless they either begin to move on--to which it fades--or they completely stop--causing it to disappear all together. 
However, if they're ready to confess to their crush, the colour shifts to a brilliant white. But if they decide to keep their heart to themselves, the colour changes to a dark pink before vanishing altogether.

So when Suga awakens to find a vibrant blue on his nails, he can't help but search out for the one who loves him admist a country of brown eyes.