This Protagonist Is Dangerous

From the start, his girlfriend steals his partner, making him the laughingstock of the entire school. Then a mysterious CEO suddenly shows up, claims to be his older sister, brings news of his long-missing older brother, and gives him a jade pendant.

Through it, he inherits the knowledge of medicine. Now, he will take back everything that belongs to him. Those who abandon him will regret it for the rest of their lives! Those who humiliate him will beg for death, yet be unable to die!