In Act Zero was a single episode of Pretty Guardian Moon, which told how Minako Aino and Artemis first became a team, and about their first mission to protect Usagi Tsukino from a group of eccentric jewel thieves.
A sequel to the series, set four years later, that portrays the wedding of Mamoru and Usagi. Before their nuptials they must do battle with Mio Kuroki who has been resurrected and claims to be the new queen of the Dark Kingdom. She kidnaps Mamoru and Usagi and intends to force Mamoru to marry her. However, the Shitennou are revived and help their master to defeat Mio's youma, Sword and Shield. Meanwhile, the Sailor Senshi, minus Sailor Mars who is hospitalized with injuries from battling Mio while in her civilian state, use the Moon Sword provided by Queen Serenity to restore their power, enabling them to transform and face Mio.
