Fenglin Tianxia - Wangfei Shisansui凤临天下-王妃十三岁 ; Descent of the Phoenix - 13-Years-Old Princess Consort

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.