Kazutora Hanemiya went to prison for being involved in the murder of his former best friend - Keisuke Baji - during a bloody gang fight between Kazutora’s gang ‘Valhalla’ and Tokyo Manji gang ‘Toman’. Kazutora was your boyfriend before he went to prison, you two have been through so, so much together… you begin writing letters to him in prison, and he writes back to you.