In many Japanese myths, the hero or heroine is confronted by a talking animal that either causes mischief or grants good luck. Talking cats are usually said to bring misfortune. I wonder how Usagi and Minako feel about that...
While the circumstances surrounding Japanese heroines varies, almost all have one characteristic in common: all are faithful to their lover, even after death. Selenity/Usagi is the perfect example. During the Silver Millennium, she refuse to leave Prince Endymion's side. She watched him die and, as Queen Selenity says: "Overcome with sorrow, you took your own life." During the battle with Metallia, Usagi is forced to kill Mamoru in order to break the evil spell cast on him. As he dies, she plunges the sword into her own body, committing hara kiri. While she doesn't kill herself in the Sailor Stars arc, Usagi resists all of Seiya's advances, believing that her Mamo-chan would return to her someday.
The mirror, sword, and jewels are important parts of Japanese mythology. They are the imperial regalia of the family of the sun goddess.
Once, the sun goddess Amaterasu was insulted by her brother Susamo, the storm god. She hid herself in a cave, bringing darkness to the world. Susamo devised a plan to get her to come outside. He placed a mirror outside the cave and coaxed her out. When Amaterasu finally came out, she saw her reflection in the mirror and was pleased.
A dragon was holding a minor goddess hostage. Susamo heard about her plight and went to rescue her. He slay the dragon and found a sword hidden in its tail. When Susamo brought the sword to his sister, Amaterasu was so taken with it, she traded some jewels for the sword.