The Digital World is becoming so overpopulated that the super computer Yggdrasill who governs the Digital World can no longer handle it. Its solution is Project Ark: to wipe out most of inhabitants with the X Program. Yggdrasill chooses a very small percentage to be moved to a new Digital World and then proceeds to destroy the old one. Some Digimon who were not chosen survive anyway, and they move to the new world with a rare gift known as the X Antibody; this antibody changes their appearance and makes them more powerful, while at the same time making them immune to the X Program. No longer in control, Yggdrasill uses the Royal Knights to destroy these X-Digimon, who are outcasts in the new Digital World.

One peaceful day on Earth, two remnants of Frieza's army named Sorbet and Tagoma arrive searching for the Dragon Balls with the aim of reviving Frieza. They succeed, and Frieza subsequently seeks revenge on the Saiyans.

Just when Usagi Tsukino thought life would be back to normal a little girl literally falls out of the sky. The girl has a striking resemblance to Usagi and even shares the same name as her. Turns out Chibiusa is from the future and she is on a mission to find the Silver Crystal that could help save her timeline from an evil threat. However she is being hunted by members of the Dark Moon Clan who were behind attacking her home world. It is up to Sailor Moon and the Sailor Guardians to help protect Chibiusa and save the future.

Usagi thinks life may be back to normal when a little girl literally falls out of the sky. She also calls herself Usagi and she seeks the help of Sailor Moon and the Sailor Guardians to help her save the future. When the Dark Moon attacks modern-time Japan, it looks like the threats of the future are also out to destroy the past.