As a first-year law student, Lee Yeon never expected to cross paths again with his middle school crush — the charming upperclassman Hong Kihoon. But a chance reunion on campus leads to an even more unexpected twist: a spontaneous trip, and a strange challenge known only as the Red Thread Quest. Red Thread Quest, Round 1: Five Kisses on the Cheek! Skeptical about soulmates and fate, Yeon finds himself drawn into the legend of the Red Thread of Fate — and as each round of the quest unfolds, his relationship with Kihoon begins to take an unpredictable turn. What started as a game might just lead them to something real…if the Red Thread Rock has anything to say about it.