Min Jun's work life is disrupted when his ex Jin Hwan, who broke his heart years ago, joins the office, reigniting mixed emotions and unresolved feelings.

Minjun finds himself drawn to Jinhwan's confidence, stirred by his kind words during a meeting where Jinhwan asks, "Do you think love comes with a manual?"

As they continue to spend time together working, the memories of the arc of of their past relationship resurface, and the truth as to why they broke up gradually gets revealed.

After insisting on sending Min Jun home one night, Jin Hwan draws closer to his previous relationship, and when Min Jun confesses, the two kiss. What happens when the two wake up together the next day?

While their feelings for each other have become clear, their relationship is anything but. Jin Hwan tries to be brave, but Min Jun has cooled and backed away for fear of getting hurt again. Jin Hwan resigns and prepares to go abroad; will Min Jun be able to rush to the airport and save the relationship he truly wants?

As they reach their one-year anniversary, Min Jun prepares a gift and Jin Hwan arranges a dinner. Jin Hwan suggests that the two move in together, but Min Jun is apprehensive about the future. Will these two finally be able to come to an understanding after one -year of being together?