In the near future, public order is on a continual decline due to the clandestine machinations of the evil organization known as Joker.
In order to protect the well-being of their society, Aigis Pink (AKA: Momo Aikawa) and Aigis Blue (AKA: Kotoha Aoi)—both belonging to the public safety organization known as Tritonis—spend their days working as a team to carry out myriad missions.
One day, frustrated by her work being impeded by their chief Gandai and his wishy-washy attitude toward the eradication of Joker, Aigis Blue ventures alone to Joker’s hideout, which she had located in secret. However, she never returns.
One month later, growing increasingly concerned for her partner, Aigis Pink ignores Chief Gandai’s orders and begins looking into the whereabouts of Aigis Blue…