Princess Medical Doctor - Chapter 1: Forced marriage and a slap

Cho Ryu Hyang was good at math from a young age. When he enrolled into the The Theoretical Maths and Martial Arts School, the teacher, Jo Gi Chun, recognized Cho Ryu Hyang’s talent immediately and took him in.

Huang Dan’s pain nerve is innately different from the ordinary people. A little tore in his skin can cause him to sweat all over his body painfully to the point of him unable to make a word out.

Somehow, he began to cross world, following Mr. System to do the tasks…

In the first world, Huang Dan realizes what it means to die painfully and to live to die again.

TL’s summary:
MC suddenly transmigrated and is bind to a system, requiring him to solve mysteries. Born with a higher degree of pain sensitivity, he met different people in the different worlds and learns what kind of emotion smiling is.

- Description from Novelupdates

Upon meeting the girl who would become her adopted younger sister, the duke’s daughter Christina regained memories of her previous life. Through those memories, she learned that her new sister, Mishuli, was the heroine of a certain story. And though the story depicted a Christina who abused her sister, the real Christina turned into a siscon who spoiled Mishuli to no end.

This is the story of Long Yi, who was killed because he took revenge for the girl he loved. Before he dies, a strange lightning carries his soul into a different realm. How will he live, when the first thing he noticed upon arrival is that, the man whose body he possessed is raping the country’s princess?

- Description from Novelupdates