After I Was Reborn, My Sister Traded Her Beauty for My Intelligence

I was ugly from childhood, but exceptionally intelligent. My twin sister was the complete opposite: stunningly beautiful, but hopeless at school. In my previous life, she fell in with the wrong crowd and got pregnant before marriage. I used my intelligence to turn my life around and became the top scorer on the college entrance exam, but my sister murdered me and dumped my body. In this new life, my sister binds herself to an exchange System. She trades her beauty for my intelligence.