Masugu Tateishi works in the accounting department of Tsuda Confectionery, a sweets manufacturing company. His relationship with Yui Mitsuya—a coworker who joined the company at the same time but works in the planning department—is particularly hostile, to the point that their frequent clashes earn them the office nickname "mortal enemies". In reality, however, the two are deeply attracted to each other, and after a series of twists and turns, they finally become a couple. Despite their feelings, Yui worries about workplace gossip and the challenges of office romance. To avoid scrutiny, they agree to keep their relationship a secret. Thus begins their covert life as coworkers-turned-lovers, all while maintaining their carefully crafted façade of mutual dislike in the office.
