Two months after the final battle against Queen Beryl, a mysterious meteorite crashes near the Tsukino household. The next day, two students transfer into Usagi's school, Seijuro and Natsumi. They are really Ali and En, two aliens that arrived in the meteorite crash. Although they pretend to be siblings while at school, they are really lovers. They quickly grow jealous of each other as Ali falls for Usagi and En falls for Mamoru. They need life energy to feed their Doom Tree so they create a monster to steal energy from humans. After Luna and Artemis realized that they can't handle the cardian by themselves, Luna restores Usagi's memories, and she becomes Sailor moon once again. Although she defeats the monster, Usagi regrets regaining her memories because neither Mamoru nor the other girls remember their past together.