The game is based on the Japanese manga and anime series Sailor Moon. It is set in the 30th century, in a futuristic city Crystal Tokyo. In this city lives a totally ordinary (at first) fourteen-year old girl Usagi. When she meets a magical cat named Luna, she finds out that she is in fact a princess sent to the future in order to fight the minions of Darkness. She discovers within herself the power to transform into the hero of darkness, Sailor Moon, meets other warriors who help her on her quest, and fights the evil Queen Beryl, hostile aliens, and other foes.
The events of this game take place shortly after Bishōjo Senshi Sailor Moon S, the fourth volume of the long-running series. A global peace is established in the universe, but lately suspicious things are happening. A strange meteorite is seen approaching the Earth. Street gangs and spies who work for a mysterious person called Apsu are seen in Crystal Tokyo. And the Mystic Silver Crystal, the Ginzuishou, which protects the city, is shaking! Usagi and her friends must now investigate the strange events and face the forces of Darkness once again.
The game is a Japanese-style RPG in Final Fantasy style (battles with your party to the right and the enemies to the left), with a battle system somewhat similar to that of Chrono Trigger: you must form a party out of several available characters, make them participate in battles together, and learn powerful combo attacks.