In this world, there's no such thing as color. Well, that's not entirely true. The only color that you can see besides gray is your soulmate's eye color. Teenager Lovino Vargas has only ever seen vivid green amongst everything else being gray. And when he finally meets somebody with that eye color for the first time, he's unsure of what to do. Meanwhile, Tino Vainamoinen sees blue. He has longed for the day he will meet his soulmate for as long as he can remember. He's about to give up all hope until one day, his dream finally comes true. But him and his soulmate are very different from each other. Tino's best friend Mathias Kohler passes by his own soulmate in the hallway every day. But they've never spoken and he always misses opportunities to catch up to him. When they finally meet up, he realizes there's more to this blue-eyed fellow than it appears. He seems to have some odd important secrets. Shy student Kiku Honda doesn't have any friends. He's basically as far from popular as you can get. But he quite literally runs into his soulmate on the street...and he happens to be the most popular guy in school! This group of mismatched soulmates, along with a few others, eventually meets. With their newfound friendship, they decide to help each other with relationships and friendship issues. And Mathias' soulmate seems to have an interesting plan that could benefit the world. But how are the others involved?