Struggling real-life couples date each other's partners to decide who to leave with: the same person they walked in with or someone new.

Yeon-woo, neurologically colorblind, sees colors through Yoo-han in a "color rush." Their connection intertwines with the mystery of his missing mother.

Yeon Woo sees only black and white—until finding his missing “probe” soulmate who could restore his color. With secrets, love, and others searching too, the truth awaits.

Yeon Woo lives in a grey world as a Mono—until meeting Yoo Han triggers his first Color Rush. Afraid of obsession, Yeon Woo resists, but Yoo Han won’t let go.