Based on

Movies like THE RAPIST: Beautiful Sisters' Cry of Skin (2010)

Mana and Mai were subjected to a terrible event a year ago. They were forcibly abducted into a van and sexually assaulted by the men they didn't know. A video camera was recording them the whole time. Mana managed to escape, but Mai was left out. A letter arrives for Mana who is still haunted by what happened...