Keroro Gunsou Movie 2: Shinkai no Princess de Arimasu!

After Momoka gives Fuyuki a strange creature in a jar, the Keroro Platoon and friends head to a South Pacific island for a holiday; but on the first night there, the group is attacked by giant sea creatures that kidnap Natsumi! When she regains consciousness, Natsumi is greeted by two aliens: Maru, a female, and Meru, a male who makes Natsumi his princess and creates a deep-sea world from her memories. Meanwhile, Keroro and the others must now figure out who these two aliens are, think of a way to rescue Natsumi, and perhaps save the world from flooding whilst they’re at it!