Before joining the Diamondbacks, the 35-year-old Hirano spent 11 seasons pitching in Japan for Orix of Japan's Pacific League.

Hirano can earn $500,000 in bonuses based on pitching appearances: $50,000 each for 30 and 35, $75,000 apiece for 45 and 50, $100,000 for 55 and $150,000 for 60.
He also can get $450,000 in bonuses for games finished: $50,000 for 20, $75,000 apiece for 25 and 30, $100,000 for 35 and $150,000 for 40.
Hirano would receive a $250,000 assignment bonus each time he is traded but not if he is claimed on waivers, the money payable by the new team. Hirano cannot be sent to the minor leagues without his consent.