Fenglin Tianxia - Wangfei Shisansui

From Shiroyukineko Translations: The strongest female assassin from a special assassination force met her death one day on a mission. To her surprise, she woke up in the body of a 13 year old girl, Mu Rong Liu Yue. Through Liu Yue's past memories, she found out that she was bullied due to the huge birthmark on her face, even though she came from a renowned family.