One day, Papa said that we are going to take in a child from a distant relative. His name is Souji Ando, he is the same age as me and a middle school student. At first, I was taken aback by the sudden change and tried to keep my distance from Souji-kun, but not long after, I found myself interested to Souji-kun. He is very nice, smart, , serious, handsome, and has a very gentle smile. On top of that, his singing voice is really captivating. My school life was really boring and dull before, but as I experience my first love, I started to enjoy my every day life. However, Mama treats Souji-kun very coldly at home, while my little sister, Emi, shows no interest and treats him as if he doesn’t exist. Keeping it a secret from my family, I gradually get closer and closer with Souji-kun. Then, both me and Souji-kun eventually graduated from middle school and go onto high school. I thought that these happy days would last forever, but for some reason, Souji-kun starts to acts cold towards me, distance himself from me and leave home. Then one day, I finally learned about the true relationship between Souji-kun and me. I also learn about the sins of my parents, and as well as the sin of my own existence. Upon learning these sins, I made a firm decision. I wonder what lies ahead of my decision, will it be misery or happiness?