Kanami

Kanami has always been sickly, and neglected by her parents. For most of her life, she has depended on her older brother to care for her, help her, and pay attention to her when she needed it. Slowly, her sisterly feelings became something else. Time stops for no one; just as children grow independent from their parents, siblings eventually drift apart. Kanami, on learning of her brother's girlfriend, finds that her feelings were far deeper, and far darker than she realized.

summary from http://games.clone-army.org/kanami_vn.php