It is Modern Day Japan.

In one part of Tokyo, a young brunette with two large buns on either side of her head resides with her beloved. She and her best friend had just returned from a book - a strange book, with sucked them back into Imperial China, becoming Priestesses of their designated God, with the option of any wish of their heart's desire. With their friendship strained, they are just becoming good friends once again. She is Miaka Yuuki, the former Suzaku no Miko, now just a regular girl.

In another part of Tokyo, a blonde with a similar hairstyle hangs with her friends. She is Tsukino Usagi...or the Pretty Sailor-suited Soldier Sailormoon. Her future and her legacy is a prolific one - she is a princess from the Moon, and soon to be the Queen of Crystal Tokyo. Her friends are also Princesses as well. When the time comes, they transform into beautiful young soldiers wearing a short seifuku - known as the Sailor Senshi. They have had no need to transform now, living in a world of relative peace, since their last crisis, known as the Sailor Wars.

Now, however, a new menace is taking form - with it's origins being from Ancient China, and seeping through an ancient text into Tokyo - and can possibly infest the entire world, stealing stones from the hearts and chi of regular bystanders in hopes to come up with the Black Diamond - a large, impure stone with great destructive power, with the potential to not only warp time, but destroy humanity as the characters know it, starting from Ancient China, and even causing threats in the present.