What is Other Planet manga?
The anime will fit this category if some or all of the action takes place on another planet which is supposedly in the same universe as Earth, not a complete fantasy world; usually there has to be some concept of space travel. The Latin name for Earth - Terra, would also pass the condition of being in the same universe as Earth. Basically, even mentioning of Earth existing or having existed would be enough. Although Moon is a moon, it also qualifies as Other Planet.