 Queen Beryl may be gone, but Sailor Moon will find herself facing a new kind of threat when two alien beings named Allan and Ann land on her home world with the Dune Tree, a plant-like being that thrives on human energy for survival. The Dune Tree is a vassal that Allan and Ann need to survive on because they are the last two of their kind and if the Dune Tree dies, they die. Using ferocious energy hunting beings called  Cardians  Ann and Allan prepare their hunt for energy and Luna must make a choice as to whether or not she should revive Serena of her past memories to combat this threat. However, Ann and Allan s unity with each other will definitely be in turmoil when they disguise themselves as a  brother & sister  duo at Serena s school; with Allan falling in love with Serena and Ann falling in love with Darien.