"Big Money!" is a human drama with a suspense twist about a young man who learns the tricks of the trade about stock exchange from a well-experienced investor. The backdrop of this story is the elaborate world of banking and the stock market.

Shirato Norimichi (Nagase) lives off the money his parents send him, and his winnings at pachinko while waiting to find permanent employment. One day, Shirato is recruited by a mysterious elderly gentleman by the name of Kozuka Taihei (Ueki). Shirato later finds out that the small, yet mild mannered Kozuka was once a legendary trader.

Although clouded by the mystery surrounding Kozuka, Shirato begins to work for him. In time, Shirato finds himself being mesmerized by the wave of numbers of the market.

Sometime later, Shirato learns Kozuka's real intentions...he wants to bankrupt one of the world's leading banks, Matsuba Bank.

The two men of very different ages then try to go up against Matsuba and the elite bankers that work at the giant Matsuba such as Yamazaki Fumihiko (Harada).