In a near-future Japan where gambling on mahjong has been legalized on the grounds of a research report claiming it can prevent dementia, corporate warriors engage in high-stakes matches that determine the fate of their companies. The story centers on Kazami Construction, a rapidly rising general contractor that presents a clean, white-collar image to the public. Behind this facade, the real engine of the company's explosive growth is its hidden Corporate Entertainment Mahjong Department, known as the Settai Mahjong-ka. New employee Suzume is assigned to this division and discovers a world where employees engage in deadly serious mahjong matches with the specific goal of strategically losing. The department plays to secure advantageous bids on construction contracts, which are the lifeline of the industry. Rather than aiming for victory, members use razor-sharp reads and split-second judgment to lose in a calculated manner, a level of precision impossible in ordinary mahjong played simply to win. Key figures include Suzume, a newcomer drawn into the high-pressure environment; Akazawa, a former professional mahjong player who left the pro circuit due to a figure named Togai; and Togai himself, who resurfaces as a rival in a high-stakes competition. The narrative follows the department through escalating challenges, including a final-phase entertainment mahjong competition for a massive project contract, where Akazawa faces Togai in a decisive match. Meanwhile, suspicions of a spy within the Marketing Communications Department emerge after a top official from the Shin-Ma-tori division makes a cryptic prediction about Suzume's upcoming business trip with Akazawa. The story blends corporate maneuvering, psychological tension, and mahjong strategy in a near-future business suspense setting.