High school girl agent Rindo Shindo, codename Bull Seller Striker, possesses extraordinary abilities and has repeatedly thwarted evil conspiracies, making her a hated figure among criminal organizations. One day, she is approached by Jaryu, a high-ranking member of the drug syndicate Snake Fang, who requests her assistance in developing a new assassination weapon. Having had his plans repeatedly sabotaged by Bull Seller Striker, Jaryu devises a new strategy—creating a killing machine. The assassin chosen to pilot this machine is Kirihito, a modified version of Shinichi Shindo, once the top-level agent and Rindo's predecessor. Now, Bull Seller Striker must face off against this ultimate killing machine. What follows escalates into a full-scale battle between evil schemes and justice.