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!
Uruno, a failure of a wolf, is currently traveling to find himself a new place to call home; but upon chancing across a rabbit, he attacks it only to realize that this particular rabbit is stronger than any predator! Soon afterwards he discovers that this entire forest he has come across is home to similar 'useless animals' that are atypical of their species. He decides to stick around when he meets his love interest in the form of a clumsy cheetah, and with his new friends, he meets the rest of the animals in the forest, causing much hijinx and fun in the process!
OK, so one may be about aliens trying to take over the world and the other about useless animals, but bear with me. My reason for recommending Damekko Doubutsu if you liked the second Keroro Gunsou movie, is because both have a similar and harmless kind of humour about them. While the second Keroro movie is a bit more random, if you enjoyed it then it may be worthwhile taking a look at Damekko Doubutsu