Rivals since high school, Yotsuya Ryo and Shito Zen have always measured their worth against each other. Their competition has spanned everything from test scores and sports to the number of Valentine's chocolates each received. After graduation, they lose touch until they end up working at the same company as salesmen in different departments. The rivalry reignites immediately. Their current bet revolves around sales performance, with the rule that the loser must obey the winner's command. When Zen loses, Ryo drags him out for drinks. As alcohol loosens their tongues, a jealous argument about romantic experience devolves into a childish challenge to see who can last longer during a mutual sexual act. The physical encounter goes further than either expected, and afterward, neither can back down. They escalate into a new, self-destructive wager: whoever falls in love first loses. Ryo secretly understands the danger, because he has been in love with Zen since high school. Zen, more oblivious, treats the bet as yet another competition. Their daily life becomes a game of flirtation, manipulation, and one-upmanship carried out in offices, after-work bars, and hotels. Each attempt to be more seductive than the other only pulls them closer, forcing both to confront the line between pretending to care and actually caring. In the subsequent story arcs, the pair tentatively transitions from rivals into a couple. The sequel, Fake Fact Lips break, explores the growing pains of their relationship. A colleague named Futami returns from a transfer and suspects their secret, prompting Ryo and Zen to openly declare their relationship. Work stress, jealousy, and insecurity test their bond. Ryo, long aware of his feelings, begins to express his affection more directly, while Zen gradually learns to articulate his own emotions. Their dysfunctional pattern of competing never fully disappears, but it shifts into a familiar, private language that sustains their connection.