The seventeenth princess of Xing (the lowest ranked house), who like Ling Yao, travels west searching for the Philosopher's Stone so she can become the empress and secure the future of her family.
She travels along with her pet mini-panda, Xiao Mei. Adept at Xing's style of alchemy, called Alchahastry, she use throwing knives to arrange transmutation circles in order to manipulate targets at long range.
A ardent fan of Edward Elric because of the way he helps people with alchemy, her image of him is quickly shattered when she sees him in person. Not knowing the history of the conflict between Scar and Edward, Mei helps Scar escape from the Emestrian military when the tide of battle turns against him, and begins traveling with him afterwards.
Though she becomes disillusioned with Edward soon after meeting him, she quickly becomes enamored with Alphonse instead.
Upon concluding the series, she is seen in a picture (the same in which we see a married Ed and Winry) with Al, so it's assumed that they married.