Chapter 4

Mustn't Lose is the fourth chapter of the JoJo's Bizarre Adventure manga. It is also the fourth chapter of Part I: Phantom Blood.

Summary
After kissing her, Dio throws Erina to the ground and declares that her first kiss came from him and not from Jonathan. In tears, Erina washes her face in a puddle of gutter water. Knowing this to be an insult, Dio slaps her to the ground and leaves.

Later, back at the mansion, George and Dio are watching Jonathan play with Danny. George says that Jonathan and Danny's relationship isn't just that of a master and his dog, but one of true friendship. Dio is perplexed by the idea of friendship with a dog. George says that back when Jonathan was five, he bought Danny for Jonathan. Danny was unfamiliar with strange places and people, and would bite Jonathan's arm when he tried to pet him. Out of fright, Jonathan would throw rocks and other things at Danny. However, one day, Danny saved Jonathan from drowning in a river. It was that event that allowed their friendship to begin.

Later, Jonathan sees Erina and calls out her, but she runs away, not ready to face him. After hearing from some of his former friends what happened between Dio and Erina, Jonathan rushes into the mansion screaming Dio's name. He strikes Dio, but Dio is able to easily elbow him. Jonathan becomes determined not to lose this fight, because if he does he will have to live in Dio's shadow for the rest of his life. They punch each other furiously and Jonathan tells Dio that he won't stop hitting him until he cries.