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 did not come from Jonathan but instead it was him. A crying Erina soon begins to wash her face in a puddle of gutter water. Knowing this to be an insult to himself, Dio slaps Erina to the ground and leaves right afterwards.

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 of a master and his dog but of true friendship. George says that back when Jonathan was five, he bought Danny for Jonathan. Danny was, however, unfamiliar with strange places and people and so Danny would bite Jonathan's arm when he tried to pet him. Out of fright, Jonathan would throw rocks at Danny and other things. However, one day at the river, Jonathan was drowning and Danny came rushing in and saved him. It was that event that allowed their friendship to begin.

At another time, Jonathan sees Erina and tries calling out her. But she runs away, not ready to face Jonathan. After hearing what happened between Dio & Erina by some of his former friends, Jonathan comes rushing back into the mansion screaming Dio's name. Jonathan soon begins to hit Dio but Dio is able to easily elbow him. Jonathan then becomes determined not to lose this fight, because if he does he'd have to live in Dio's shadow for the rest of his life. They each give each other furious punches and Jonathan says to Dio that, until Dio cries, he won't stop hitting him.