Amy Anderson/Early Life

Princess Mercury (プリンセス・セレニティ) is the previous life of the reincarnated Amy Anderson. Princess Mercury was a subject of Queen Serenity, and the princess of Mercury.

Princess of Mercury
The Princess of Mercury was one of the many subjects of the Moon Kingdom. She also acted as warrior for both Mercury and the Moon's princess, Serena. When the Negaverse and Queen Beryl attacked the Moon Kingdom, Mercury was killed in battle alongside the other Sailor Scouts, inner and outer alike.

After Queen Serenity sealed away the Beryl and the Negaverse, she used the last of her power in conjunction with the Imperium Silver Crystal to send Mercury and the other subjects of the Moon Kingdom to Earth to be reborn.