Josuke Higashikata is the primary protagonist of the fourth story arc of JoJo's Bizarre Adventure, Diamond is Unbreakable. He is a sixteen-year-old high school student residing in the fictional Japanese town of Morioh. Josuke is the illegitimate son of Joseph Joestar, having been conceived during Joseph's later years through an affair with a young Japanese woman named Tomoko Higashikata. Because Joseph was absent throughout his childhood, Josuke was raised solely by his mother. This family connection makes him the half-uncle of Jotaro Kujo, who is twelve years older than him.

Josuke stands out with a distinctive and carefully styled pompadour hairstyle, which he maintains as a tribute to a mysterious stranger who saved his life when he was a child. He typically wears a modified Japanese school uniform and is notably tall for his age. His personality is a mixture of a generally kind-hearted, polite, and sociable nature with an explosive and violent temper when provoked. The most reliable way to incite his anger is to insult his hair, a trigger that sends him into a blind rage where he can become literally blinded by fury. Despite this fierce temper, he is fundamentally compassionate and prefers to talk through problems rather than resort to violence when possible.

Josuke's motivations are deeply rooted in a sense of justice instilled in him by his maternal grandfather, Ryohei Higashikata, who was a police officer. Initially reluctant to get involved in conflicts with Stand users, Josuke's perspective changes forever after a criminal Stand user named Angelo murders his grandfather. Taking on his grandfathers will, he vows to protect his hometown of Morioh from evil Stand users. This sense of duty leads him into the central conflict of the story: hunting down the town's resident serial killer, Yoshikage Kira.

His role in the story is that of a leader and uniting force for Moriohs heroes. Jotaro Kujo comes to Morioh specifically because he learns of Josuke's existence and warns him about the dangers of Stand users in the area. Throughout the narrative, Josuke befriends and earns the loyalty of other Stand users, including the timid but brave Koichi Hirose and the rough but good-hearted Okuyasu Nijimura. His sincere and soft-hearted nature even influences initially antagonistic characters like the egotistical manga artist Rohan Kishibe and the obsessive Yukako Yamagishi to become allies. His relationship with his father, Joseph Joestar, is complex; Josuke initially harbors resentment over being abandoned but eventually shows compassion toward the aging man and accepts him as family, playfully calling him old man.

Josuke is a quick-thinking and inventive fighter, and his development throughout the story sees him grow from a reluctant participant to a determined and selfless protector of his town. He is financially irresponsible and has a greedy streak for money, yet he is unfailingly dependable when his friends or family are in danger.

His most notable ability is his Stand, Crazy Diamond, named after the Pink Floyd song Shine On You Crazy Diamond. Crazy Diamond is a close-range, humanoid Stand with immense physical strength and speed comparable to Jotaro's Star Platinum. Its primary power is restoration. Crazy Diamond can repair broken objects and heal physical wounds by reverting them to a previous state. Josuke can use this ability in creative ways, such as restoring a shattered glass to track an enemy or fusing objects together to trap an opponent. However, the power has critical limitations: it cannot heal Josuke himself, it cannot revive the dead or cure illnesses, and if Josuke is emotionally compromised or enraged, the restoration may be malformed or imperfect.