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.