I and Rika have been dating since high school. Maybe because we have been in love for a long time, the feelings of both of us are not the same as before. Recently, Rika has started dating a senior man who is better than me in every way, making Rika feel unsettled. The man is preparing for a trip and invited Rika to go with him, she agreed and took this opportunity to confirm the current status of our relationship. Although Rika did not say anything, I still feel that something is happening. While sitting alone in the park near my house, Konan passed by. She knows everything, she sat and listened to my confessions, chatted, and helped improve my mood. On the day Rika went on the trip, she waited for me outside and suggested replacing Rika as my girlfriend for three days! And in these three days, I felt like I was back to the early days of falling in love. I got to know her better and gradually developed feelings for her. I tried to confess my feelings, but she refused. I am Rika's boyfriend, her younger sister, there will never be a result between me and her...