reign's manga / #Younger Sister(1)

[Villain's Younger Sister] ━━━ ━━━ One day, the MC opened her eyes to find herself in prison. Out of all the characters she could’ve reincarnated into, she woke up inside a 19+ rated romance novel as the Villain’s younger sister. To make matters worse, she was locked up inside the infamous Kambrakam Prison for her brother’s crimes. The ML, who suffers from a curse that turns him into a beast, lies deep within the very same prison. He’s supposed to meet the FL in 4 years, but since the MC's visits, the plot’s gone awry.