Whilst working at her job at a café, Marika Kato is approached by two people who are acquaintances of her mother, Ririka. Both of them later show up to her house that evening and reveal to Marika that her father, Gonzaemon Kato, who has recently died, was the space pirate Captain of the spaceship Bentenmaru. By the Letter of marque inheritances laws of the planet Sea of the Morning Star, in order for the Bentenmaru to continue operating legally, Marika must take over as captain of the Bentenmaru as Gonzaemon's eldest child. As a confused Marika does some research into the matter, the Bentenmaru's helmsman and medic, Kane McDougal and Misa Grandwood transfer to Marika's school as a new teacher and school doctor respectively, along with the mysterious transfer student, Chiaki Kurihara. Later at her workplace, Marika notices groups of strange men suspiciously monitoring her. When Chiaki arrives, she exposes an impostor disguise as airport security attempting to kidnap Marika and stops him by starting a gun fight in the cafe and dragging Marika to safety.