The anonymous partnership Investment Economic Association, led by its president Ryuichi Amano, collected money from many ordinary people and paid out large dividends, making it famous as "Japan's only investment bank for ordinary people." On the other hand, Detective Muneharu Matsumoto of the Metropolitan Police Department's Second Investigative Division has suspicions about this organization, and has been spying on the business association for many years. However, Matsumoto was having a hard time getting any solid proof of the nature of the incident...