Read manga: Love Survival

manga
Summary:

Seri is in love with her childhood friend, who also happens to be her next door neighbor, Kou. But Kou has been in love with Seri's beautiful older sister, Nana, ever since they were children. Seri has been asking advice from Ikushi, her classmate, about what to do. And soon Seri realizes what she has to do... What will Seri do?!