My Sister's Friend summary:
At the age of 14, her first lover was her sister's former best friend, Kyoko. It was a time where Noriko would meet Kyoko after school and be thrilled by the smell of her adult perfume and enchanting eyes, nothing like spending time with her boring classmates. But why did Kyoko and her sister stop being friends in the first place? This is the story of three women and their discovery of what true "love" entails. (Source: Leed-sha, translated)