Mei (or May, depending on the localization in the future, it may be changed) is the default name of your trainer in Pokémon Black 2 and White 2. As usual, her name will be revealed by going through the Battle Subway if your player character gender is the male trainer, which she will join you in a tag battle.
Interestingly, her name shares the same name as the main female character in the English version of RSE, although her name in the Japanese version is Haruka.
Another interesting to note is that her name was one mistakenly written as Girl (Boy) (女の子(おとこのこ)) in the official website of the game, before its release.
Her voice actress is also confirmed in the PV to be Aki Toyosaki.
Mei has brown hair and blue eyes. She wears a cycling hat and has her hair tied into two large buns. She wears an azure and white sweater with a PokéBall in the chest area, and wears a frilly flared yellow shorts. Mei wears opaque black leggings, pink socks, and azure and white shoes with yellow laces. She carries a large handbag.
Due to her hairstyle, fans related her two large buns to edible buns or Shiitake mushrooms.
When You Search...
Please ensure you use "メイ(トレーナー)" and set your search results to "Exact match" when searching. This will return the exact results for the partciular character in BW2.
As other game or anime characters have "May" or "Mei" as their name, searching without the method above will result you in various jumbled results (Like **Mei**o,**Mei**kingu Wanteddo and many other funny results).