Chapter 7

The Vow to the Father is the seventh chapter of the JoJo's Bizarre Adventure manga. It is also the seventh chapter of Part I: Phantom Blood.

Summary
Seven years previously, Dio is seen trying to give his father some medicine, only to be struck by Dario, who would rather drink alcohol than take medicine. Dario also wants Dio to sell his mother's dress, saying that he doesn't need "some dead bitch's stuff." Dio cries and resolves to kill his father. Later, Dio, wearing a mask, goes to an area of Chinatown to get some Oriental poison from a man named Wang Chan.

Back in the present, Jonathan has realized that Dio killed his father Dario and is trying to use the same poison to kill George. Dio denies this claim, but Jonathan says that he plans to investigate the medicine to see if it is legitimate. Dio tries to make Jonathan return the medicine to the tray, but he refuses. However, Jonathan says that if Dio swears his innocence on his father's honor, he will return the medicine and never speak of it again. Dio refuses, saying that someone like Dario had no honor at all. The thought of Dario causes Dio to hit Jonathan. However, the years have passed and Jonathan is much stronger now. Jonathan grabs hold of Dio and throws him down from the second story of the house to the first.

Jonathan knows now that he and Dio were never friends, and says that he will make sure to get the medicine analyzed and send Dio to jail. Dio knows it will take Jonathan at least three days to find proof of the poison, and says that he'll have to finish off Jonathan before then.