Set in the prelude to World War II, Japan's Navy faces a strategic dilemma over the construction of a new battleship. Faced with budget concerns and the threat posed by the growing power of the United States, the navy brass debates whether to proceed with the ambitious and costly Yamato project. Admiral Yamamoto, a forward-thinking officer, suspects corruption and inflated cost estimates. To expose the truth, he recruits Tadashi Kai, a brilliant but eccentric mathematician with an affinity for solving complex problems. Tasked with proving that the battleship's purported cost estimates are flawed, Kai delves deep into naval engineering and economic data, employing his mathematical prowess to challenge the established order.

As Kai investigates, he faces resistance from senior military officials invested in the battleship project. His quest for truth is further complicated by his own insecurities and the skepticism of his peers. Even as he strives to expose the financial and strategic pitfalls of the Yamato, he uncovers a web of vested interests that seek to silence him. Each step closer to unveiling the real cost of building the colossal warship brings greater peril, ultimately highlighting the tension between innovation and tradition in a nation gearing up for war. The investigation becomes not just a battle of numbers, but a showdown of ideologies, setting the stage for far-reaching consequences.