Jotaro is the main protagonist of the third arc, Stardust Crusaders. He is the grandson of Joseph Joestar, the main protagonist of the second arc, Battle Tendency. His mother is Holly Joestar, and his father is a bandsman who is never at home. Jotaro has a short temper, and is mostly silent.
Jotaro used to be a good kid. His mother took good care of him while his father is away.
Jotaro's Stand, Star Platinum awakened while he was at high school. He was afraid that he might be possessed by an evil spirit and decided to lock himself in a prison cell. His mother Holly called Joseph to explain the phenomenon.
At school, Jotaro discovered that Noriaki Kakyoin was the wielder of the Stand Hierophant Green. Jotaro defeated Kakyoin and removed Dio's mind-control parasite from him. Kakyoin then joined Jotaro to confront Dio.
Later, Holly developed a plant-like Stand. She wasn't strong enough to wield it and it started eating away at her life. Joseph explained that Dio Brando, an ancient enemy, has awakened to his Stand as well. He explained that defeating Dio will remove the Stand from Holly. Thus Jotaro, Joseph, Kakyoin, and Muhammad Abdul decided to travel to Egypt to defeat Dio.
At Hong Kong, the group met Jean Pierre Polnareff who wields the Stand Silver Chariot. Muhammad Abdul dueled him and won. Polnareff wanted to die as a warrior but Abdul recognized Polnareff's chivalry. Jotaro removed the mind-control parasite from Polnareff as well. Polnareff then joined them to confront Dio.
At the Nile River, the Speedwagon Foundation sent them another ally in the form of the dog Iggy, wielder of The Fool.
Finally at Cairo, Egypt, the group confronted Dio. Dio brought the fight to the streets. When Dio attempted the final attack on Jotaro by dropping a steamroller, Jotaro discovered his ability to stop time to escape from under the steamroller. He then landed the fatal blow on Dio, killing him for good.
Jotaro graduated with Ph.D. in marine biology. He eventually married and had a daughter named Jolyne Kujo. Due to his busy schedule, he couldn't spend much time with her.
Diamond is Unbreakable
Jotaro went to Morioh on Joseph's request to meet Joseph's illegitimate son Josuke Higashikata. Eventually he learned that the town housed several bows and arrows and he was determined to hunt them down. Jotaro also assisted Josuke in several battles.
Jotaro sent Koichi to investigate Giorno Giovanna.
Jotaro visited his daughter Jolyne in jail then assisted her to fight against the main antagonist Enrico Pucci.
Jotaro's Stand, Star Platinum has superhuman strength, speed, and accuracy as well as the ability to stop time for a brief period, though it's notably less capable than Dio's The World in that regard. Star Platinum also has extremely sharp hearing and sight and can also extend its index finger.
Jotaro's battle cry is "Ora Ora", which is shared by his daughter Jolyne. Jotaro is also famous for his line "Yare Yare Daze", which loosely translates to "give me a break".