Sarah is a pirate knight known for her brutal reputation in a galaxy that is going through hard times after a long war. In search of the "sword of Bernstein" and striving to occupy the imperial throne, Sarah embarks on a journey through the galaxy.

The main character of this story will be student Masaru. One day, he was returning home when his foster mother asked him to stop by her sister Miyuki's place and pick up something from her house.