Space Adventure Cobra (movie, 1982)

Having gone to ground for two years, Cobra comes out of hiding after an encounter with the bounty hunter Jane Flower and is drawn into direct confrontation with the Galactic Guild, a vast criminal organization lead by Lord Necron, a macabre representation of re-animated death. On Jane's asking the duo travel to a prison planet called Seedo and Cobra breaks into the floating prison where Jane's sister Catherine is held, but the latter doesn't want to be saved... Jane and her identical sisters Catherine and Dominique are the embodiment of the future ruler of a freely wandering planet called Myras. Should they fall in love with the same man they will meld into a single body, forming the planet's queen. Said planet has recovered from a genocide bomb that wiped out its inhabitants, and they are ready to reclaim it. Necron, though, wants to take advantage of Myras' wandering nature to crash it into the seventh galaxy's principle supernova and obliterate all life.