Oldboy -2003- !!better!!

Why does he do it? The revelation is the "Velvet Underground" of plot twists. We learn that in high school, Dae-su spread a rumor that Woo-jin was sleeping with his own sister. The rumor was true. The sister, unable to bear the shame, killed herself. Woo-jin planned his revenge for decades. He didn’t want to kill Dae-su; he wanted to turn Dae-su into himself.

By imprisoning Dae-su for 15 years, he gave Dae-su nothing to do but obsess and train. By releasing him and having a hypnotist erase his memory, Woo-jin orchestrated a relationship between Dae-su and a young sushi chef, Mi-do. Only after Dae-su falls in love does Woo-jin reveal the truth: The Unforgivable Twist "Laugh and the world laughs with you. Weep and you weep alone." This quote adorns the film’s poster. Oldboy -2003-

When Dae-su learns that he has been tricked into sleeping with his own daughter, the film transcends mere violence and enters the realm of Greek tragedy. Dae-su falls to his knees, sobbing, begging Woo-jin to spare Mi-do the truth. He offers the only thing he has left: his tongue. To save his daughter from knowing the incest, Dae-su cuts out his own tongue with a pair of scissors. Why does he do it