Gyakuten! Ippatsuman belongs to the Time Bokan series and is the sixth installment. Set in the 1990s-era Osteandel City, Time Lease is the top corporation that provides virtually everything, including powerful robots. They proudly hold the number one spot in the international billionaire ranking for the past decade. However, there is a rival lease company in the same city named Skull Lease, where the infamous villain group serves as top executives. Their objective is to disgrace Time Lease's credibility and replace them as the leading enterprise. In reality, their plan is to establish a foothold for world domination. When the villain trio attacks a transport robot of Time Lease, it's up to Ippatsuman to fight for justice.