Karasu Bank is one of Japan's leading banks, boasting the third-highest operating profits in the country. Akira Mitarai is a young employee in his second year at the bank's central branch. His exceptional math skills allow him to instantly spot accounting errors but also make his day-to-day life incredibly boring.

One day, Akira is suddenly transferred to the Special Operations Department's "Appraisal Unit," which he is told is a key department within the bank. Suspicious of his transfer and the unfamiliar department, he is told by his new boss that the bank actually operates a massive underground casino, and that the Appraisal Unit is the department responsible for managing this gambling as well as the gamblers who participate in it. But these gamblers are putting more than just their money on the line, with their very lives serving as collateral to play! Higher risk means higher rewards, but at the top level losing is a death sentence.

Overwhelmed and confused by the strange state of the bank's secret casino, Mitarai meets a mysterious, genius gambler, Shin Mafutsu. Enraptured by Shin's ability to see through his opponents' cheating and emerge victorious, Akira decides to enter the world of life-or-death gambling as Shin's bank representative.

(Source: MAL News)