Keroro Gunsou Movie 5: Tanjou! Kyuukyoku Keroro, Kiseki no Jikuu-jima, de Arimasu!!

超剧场版 Keroro军曹 诞生！究极Keroro奇迹的时空之岛！！

One day, a stone carving bearing an uncanny likeness to Keroro arrives at Fuyumi's place. To solve this mystery, the Keroro Squad travels to the isolated and mysterious Easter Island. There, they meet harmless spirits known as Mana, and the odd twins Io and Rana. Lastly, there is Akuaku, a legendary evil spirit recently awoken from its long sleep. (Source: AniDB)