Johnathan Joestar, once just the British son, and sole heir of the extremely,wealthy Joestar family, until his father George Joestar, adopted the sinister Dio Brando. Soon the two ''brothers'' find themselves in constant struggle thought out most of their childhood caused by Dio trying to get the Joestar fortune by making his Johnathan go crazy.
Once into adulthood though Dio soon evil is shown fully and soon Dio becomes a vampire bent on world control. Now, it's up to Johnathan, and a few friends to stop Dio and his rising army of vampire zombie.
We first see Jonathan Joestar as he's trying to save, and protect young aristocrat Erina Pendleton from a two bullies despite not knowing her. Johnathan is ultimately beaten by the two bullies, but they choose to leave; satisfied with the beating they gave to young JoJo. After the fight, Erina tries to help JoJo up but, he refuses her help, and claims he only helped her because it was his duty as an aspiring squire.
Shortly after the fight Johnathan goes home to find an unfamiliar carriage in front of his home. Inside is young Dio Brando who exits out of the carriage mid pose. The two quickly greet each other. Danny, Johnathan's beloved dog also come to greet the new guest, only to be brutally kick by Dio, whose reasons was a simple ''I don't like dogs''.
Johnathan's immediate reaction to this was anger, but he keeps himself calm, and doesn't attack Dio. After their first scrimmage Dio enacts his plan on making Johnathan go crazy and becoming the sole heir of the Joestar fortune. Jonathan, not knowing of Dio's wicked plans, still tries to forge a friendship with his new brother,only to be constantly bullied and insulted; soon even Jonathan's father George starts to prefer Dio over his own son.
One day JoJo invites Dio to a friendly boxing match, during the match Dio, while cheating, nearly blinds JoJo and tells all his friend that JoJo is a ''tattletale'' and shows off some fireworks. This causes all of Jonathan friends to be Dio's. Jonathan, almost completely alone, being shunned by family and former friends soon find solace once he ,meets up again with Erina Pendalton. At first she had only wanted to return a handkerchief that Jonathan gave her to clean herself after being bullied.
The two start a friendship that slowly leads to a butting romance. As their relationship grows closer, and strong, even Dio begins to notice it. Dio ,enraged at Jonathan sanity and happiness, tries to take Erina from him by forcibly kissing her. Soon Erina couldn't find it in herself to face Jonathan after Dio's kiss, she had felt ashamed and soiled.
After hearing the new, he rushes home and gives Dio an anger fueled beating,while both notice that when Dio's blood landed on the mysterious mask on the wall, spikes flew out of its back. After the humiliation of getting beat, Dio response to this is to secretly have Danny, JoJo's dog accidentally burned by a servant
Jonathan, immediately thinking it was Dio, has to ultimately let it go because of lack of proof. After this incident the two ultimately stop their constant bickering and slowly became brothers, or so it seemed. 7 year after having his dog killed and losing his developing love with Erina, Jonathan tries hard to accept Dio as his brother, but ultimately cannot truth him. Jonathan is later seen at his father George Joestar bedside as George slowly succumb to an unknown illness.
The unknown sickness is shown to be caused by Dio as a ploy to gain the Joestar riches. Jonathan learns of this by finding a note describing how Dio's farther, Dario Brando, died and from the exact sickness. To conform his suspensions JoJo testes Dio by telling him that he's going to get the medicine Dio always gave George tested in Orge Street, a dark an crime riddedled place. Dio react in a way that only showed his obvious guilt. So to gain proof Jojo sets off to Orge street Once in Orge Street, JoJo is attack by Speedwagon and his gang. He makes quick work of the the gang, but is cut by Speedwagon due to his unorthodox fighting style of using a bladed hat. Thanks to Jojo's resolve he is able to beat him with a swift kick to the face. After witnessing Jojo's resolved and restrictant, Speedwagon is decides to befriend and assists JoJo in finding the origin of Dio's.
With Speedwagon's assistance JoJo is able to finding the origin of the Dio's poison. Now, with enough proof against Dio, Jonathan rushes home with police to arrest Dio.
After confronting Dio for his crimes and nearly having his father and the police arrest him, Dio attempts to stab Jonathan with a knife in order to activate the stone mask with Jonathan's blood only to have Jonathan's father stand in the way to take the fatal attack and Dio is quickly shot down by the police after he wore the activated stone mask. Jonathan decides to talk to his dying father during his last few moments when suddenly Dio is suddenly revived as a vampire and quickly kills the police and overpowers Jonathan and Speedwagon. As a last resort, Jonathan orders Speedwagon to leave the mansion and decides to set the place on fire in order weaken Dio and nearly dies in an attempt to end his evil once and for all.
Jonathan recovers for the next few days with the help of Erina and later on meets William Anthonio Zeppeli, a man who informs him that Dio was still alive and decides to train Jonathan in the art of Hamon, a fighting style that was activated via the use of a special form of breathing and was the only way to truly defeat Dio and the forces of darkness.