Summary for the Gosenzosama Banbanzai! OVA.

Several months after a probe returning from Mars burns up during reentry, strange creatures dubbed "Ancients" begin to appear throughout Tokyo. Aggressive and dangerous, they cannot be killed with ordinary weapons. As scientists struggle to find the cause of their sudden appearance, the monsters wreak havoc across the world. Humanity finds hope in the form of the MARS suit—a new weapon developed to take down these enemies. The suit, however, can only be worn by those with specific DNA. Enter Takeru Hinata, an ordinary teen with a troubled past and one of the few capable of piloting the only weapon against the Ancients. With the help of the AAST, a special police force established to defeat the dangerous creatures, the young man battles against demons both personal and global whilst trying to discover the true nature of Earth's new aggressors.

Gyakuten! Ippatsuman is the sixth in the Time Bokan series. In the 1990s-era Osteandel City is the headquarters of Time Lease, a business that leases almost everything you could ask for including powerful robots. They are proud of themselves for being number one in the international ranking of billionaires, for the past ten consecutive years. Meanwhile there is another lease company in the same city called Skull Lease where the notorious villain trio work as top executives. Their ostensible object is to disgrace the credit of Time Lease and replace them as the leading enterprise. In fact, however, they have a scheme to secure a footing for world conquest. One day a transport robot of Time Lease is assaulted by the villain trio and it is time for Ippatsuman to get on the move to fight for justice.

Malice, a sex robot living in an abandoned human city, is assaulted and violated by a mysterious creature. Upon awakening, Malice finds out that she has become human and can pass on her humanity to her fellow machines. However, her gift soon becomes a curse when her fellow robots rage out of control after being exposed to the pleasures of life.