The third game in the Galaxy Fräulein Yuna series, Kanashimi no Sirene picks up where the last game ended. After having successfully saved the Earth, Yuna and her new friend, the ever-hungry female android Yuri Cube, return to their normal high school life - or so they think. Because her old enemies will do anything to destroy her, including wrongly accusing her of world domination plans. This draws the attention of a highly ranked female intelligence officer of the Galaxy Alliance, who operated under codename "Sirene" and who pretends to be an exchange student in the Shiraokadai High School, while her true goal is to arrest Yuna...