"3.3.7 Byooshi" is a psychological thriller manga that revolves around a high-stakes gambling game known as "337 Byooshi," a deadly variant of rock-paper-scissors. The narrative centers on a group of individuals who are forced to participate in this lethal game, where the rules are simple but the consequences are fatal. Players must choose one of three gestures—rock, paper, or scissors—within a strict time limit. Losing a round results in immediate execution, while winners advance to the next stage. The game is orchestrated by a mysterious organization with its own hidden agenda, and participants are given no choice but to comply, as their lives and the lives of their loved ones are at stake.

The protagonist, a young man named Shun Akiyama, is drawn into the game after his sister is kidnapped by the organization. Shun is an ordinary individual with no particular skills or background in gambling, but his determination to save his sister drives him to navigate the treacherous game. Along the way, he encounters other participants, each with their own motivations and backstories. These include Rei, a cold and calculating gambler with a tragic past, and Tetsuya, a former yakuza member seeking redemption. The dynamics between the characters are complex, as alliances are formed and broken under the pressure of survival.

As the game progresses, the true nature of the organization behind it begins to unravel. The participants discover that the game is not merely a sadistic form of entertainment but part of a larger, more sinister experiment designed to test human psychology and behavior under extreme stress. The stakes escalate as the number of players dwindles, and the survivors are forced to confront not only their opponents but also their own moral boundaries and fears. The narrative delves into themes of trust, betrayal, and the lengths to which people will go to survive.

The manga is structured around the progression of the game, with each round introducing new challenges and psychological twists. The tension is heightened by the constant threat of death and the unpredictable nature of the participants' decisions. The artwork complements the dark and intense atmosphere, with detailed depictions of the characters' emotions and the grim consequences of their actions. "3.3.7 Byooshi" is a gripping tale of survival and human nature, exploring the psychological toll of being pushed to one's limits in a life-or-death situation.