Read manga: Bokura No Koi Wa Shi Ni Itaru Yamai No You De

manga
Summary:

From Midnight Scans:As a child, Beniko had two close friends, Umi and Sora. They were twin brothers that lived next door but due to his "Brother-Complex" jealousy Umi stopped being friends with her and soon moved away. Sora stayed and he and Beniko devoloped a relationship but later tragedy hit as he tried to save Beniko. Umi reapears with the same voice, looks, but a more twisted personality than before. How will Beniko confront the twisted love and affection given to her by Umi, instead of from Sora?!