Josuke Higashikata is the protagonist of Part 4, "Diamond is Unbreakable." A high school student living in Morioh, he is bright and friendly but becomes extremely sensitive if anyone insults his hairstyle. He uses the Stand "Crazy Diamond," which possesses not only immense destructive power and speed but also the ability to restore broken objects or wounds to their original state. He fights various Stand users to protect his friends and the townspeople.

The protagonist of Part 8, "JoJolion," he is a young man found in Morioh with no memory of his past. His true identity is a new being born from the fusion of Yoshikage Kira and Josefumi Kujo due to the influence of the Locacaca. He uses the Stand "Soft & Wet," which can steal specific properties from objects using soap bubbles. He faces the secrets of the Higashikata family and incidents surrounding the Locacaca while searching for his identity and past.

Okuyasu Nijimura is a major character in Part 4, "Diamond is Unbreakable." Initially hostile toward Josuke, he later becomes his friend and helps solve the incidents in Morioh. Though simple-minded and impulsive, he is deeply loyal and willing to take risks for his friends. His Stand, "The Hand," has the ability to erase space with its right hand, allowing for powerful attacks and versatile maneuvers like closing the distance to an opponent or deleting objects.

Koichi Hirose is a major character in Part 4, "Diamond is Unbreakable." Initially a timid and ordinary middle school student, he gets caught up in various incidents after meeting Josuke and Okuyasu and becoming a Stand user. He grows into a strong individual, gaining courage and judgment through his experiences. His Stand is "Echoes," which has the ability to manifest sounds and sound effects in reality. It evolves through forms ACT1 to ACT3, with ACT3 being able to restrict an opponent's movement by making them incredibly heavy. Koichi uses his excellent observation skills and wit to face powerful enemies.

Jotaro Kujo is a major character in Part 4, "Diamond is Unbreakable." Having defeated DIO in Part 3, he has since become a university student and comes to Morioh to investigate Stand-related incidents. Though cool and taciturn, he acts to protect his allies and others in moments of crisis. His Stand is "Star Platinum," boasting overwhelming power, speed, and precision. While his strength has waned since his prime, he remains powerful and can use the ability to stop time. For a brief moment, time around him stops, allowing him to move freely to attack or assess the situation. As Josuke's relative and a fellow Stand user, Jotaro investigates the Morioh incidents, assists Josuke's group multiple times, and participates in the final battle against Yoshikage Kira.

Yasuho Hirose is a major character in Part 8, "JoJolion," who gives the name "Josuke" to the young man who lost his memories. She uses the Stand "Paisley Park," which assists in investigations and tracking by manipulating electronic devices and information. She is a crucial ally in uncovering Josuke's identity and the incidents in Morioh.