Slytherin's Lily

Lily Alice Evans or Alice is the only other living relative of Lily and James Potter. After the loss of her mother Alice's dad moves them to Japan where they meet her step mum Mai. Alice's contact with her aunt slowly diminishes and years after they lose contact Alice is told that her Favorite Aunt Lily isn't alive anymore and that her baby cousin Harry is living with their Aunt Petunia's family.
Alice goes through hell as she lives with her step mum Mai. But when Alice is taken away from her abusive guardian and is placed in the school her aunt loved so well, will Alice be able to keep her vow she made to her aunt?
How will Alice react when her cousin has no idea who she is?