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.

Ami, Rei, Minako and Makoto are invited to a studio to audition for a part in a new TV show. Seijuro and Natsumi are also invited, however, Usagi was not, so she decides to sneak in. Once inside, she realizes that it is a trap and a cardian is sucking the life energy out of her friends. She transforms and tries to help but is captured. Luna is forced to restore the girls' memories. Reunited again, the Sailor Warriors defeat the monster.

When a new cardian attacks a friend of Mako, she becomes hellbent on revenge. Rei uses her divination powers to discover where the cardian will attack next, and the girls go to challenge the monster. The situation turns dire, however, when the cardian defeats all of the girls and then starts to close in on Sailor Moon. Suddenly a masked man appears and throuws a white rose. He says he is the Moonlight Knight, and attacks the cardian with his sword. After Jupiter recovers and defeats the lion, the man vanishes just as mysteriously as he appeared. Usagis is heft wondering if the mystery man is really Mamoru in disguise.