Ten years ago, a young trainer went on his Island Challenge Journey. Along the way, he discovered a Pokemon named Necrozma. Necrozma came from another world, a world where there is no light. Necrozma came to Alola in order to steal the light of the Sun and Moon. It was successful for a brief period, but the young trainer defeated Necrozma and brought peace to both its world and Alola. Ten years later, something strange started happening. One day when a solar eclipse was in the forecast, the unthinkable happened. The Sun and Moon attacked each other, two celestial bodies, fighting against each other. Nobody understood what was happening, until the Aether Foundation came to a conclusion. Solgaleo and Lunala were fighting, they suspected that the other was making a move on their territory. None of the ceremonies at the Altar of Moon or the Lake of Sun have done anything to calm the Legendary Pokemon. What will happen if they battle for all eternity? The Aether Foundation believes the two Pokemon will fight to the death. If they are right, people have a feeling what will happen if either of them dies. If Solgaleo dies, the world will be covered in an eternal night, and if Lunala dies, the world will be showered by never-ending daylight. But what if they both die? What would happen to the world if both of the Legendary Pokemon die? Nobody knows for certain, but everyone agrees on one thing. It would be no exaggeration to call it the world's ruin. With the young man who brought peace to the two worlds missing, the people look towards the Island Guardians for help. The Guardians, sensing the danger that has befallen Alola, have chosen four children. They must complete their Island Trials in order to prove their strength to the Guardians. If they can, they will be able to save Alola. If not, the world will descend into ruin...