Unmei de Musubareta Koibito......no Azatoi Imouto to Issen wo Koeteshimau, Ano Hi made

"If we reunite, let's be lovers" That was the promise I made with my childhood friend, Mitsuha Mahiru a long time ago. In the spring of my second year in high school, our fateful reunion happened. We exchanged our unchanging feelings and officially became a couple. Just when I thought we could cohabitate blissfully at my place, another housemate - Mahiru's younger sister, Saya joined. One night, I was kissed by Saya, who sneaked into my room. "Shhh...be quiet. Let's keep this a secret" From that moment, the cohabitation of three filled with secrecies began - till the day I eventually crossed the line with my lover's sister.