Anime: Fushigiboshi no Futago Hime
In the hollow Mysterious Planet, seven kingdoms co-exist, all of them lit by the Suns Blessing from the Kingdom of the Sun, in the middle of the planet. The light of the core sun is necessary for the continued existence of all the kingdoms. Yet, something is causing the Suns Blessing to weaken. If something isnt done, it will be the end of life in the Mysterious Planet. Fortunately, the twin princesses of the Sun Kingdom, Fine and Rain, have been endowed with the magic of the Prominence, and are looking for a way to fix things.