Josuke Higashikata is the protagonist of the fourth story arc in the JoJo's Bizarre Adventure series, Diamond is Unbreakable. He is a Japanese high school student living in the fictional town of Morioh. Josuke is the illegitimate son of Joseph Joestar, the protagonist of the series' second arc, and a Japanese woman named Tomoko Higashikata. This makes him the half-uncle of Jotaro Kujo, the protagonist of the third arc, who is significantly closer to Josuke in age.

Josuke is a tall, physically fit teenager with a distinctive pompadour hairstyle, which is central to his identity. As a child, he and his mother were trapped in a car during a snowstorm while he suffered from a fever. A mysterious teenage stranger with a pompadour selflessly helped them, pushing the car free and placing his own coat under the tires for traction. Inspired by this act of kindness, Josuke adopted the hairstyle as a tribute to his hero. Consequently, any insult directed at his hair triggers an explosive, blind rage, causing him to violently attack the offender without hesitation.

Despite this fierce temper, Josuke is fundamentally a kind, loyal, and amiable person. His primary motivation is to protect his friends, family, and the town of Morioh. This protective nature is galvanized by the murder of his beloved grandfather, Ryohei Higashikata, a local police officer. After this loss, Josuke takes it upon himself to become the town's guardian against the growing threat of dangerous Stand users. While he is generally agreeable and can tolerate minor bullying or selfishness from others, he becomes incredibly vindictive toward those who harm his loved ones, as seen when he permanently fuses the killer Angelo with a rock as punishment. Josuke also inherits a mischievous and cunning side from his father, frequently bending or breaking rules to get what he wants, such as cheating at dice or exploiting others' powers for monetary gain.

In the story, Josuke serves as the central figure rallying a group of Stand-using allies to investigate the strange occurrences in Morioh. His role evolves from a bystander reluctantly drawn into a conflict to the town's primary defender. He works closely with Jotaro Kujo, who acts as a mentor, and forms a deep, unbreakable friendship with a fellow student named Okuyasu Nijimura, who starts as an enemy but becomes his closest companion. He also becomes a trusted ally and protector of the more timid Koichi Hirose. Josuke's complicated relationship with his father, Joseph, evolves from resentment and a desire to be left alone to a begrudging acceptance and eventual warmth after witnessing Joseph's heroic nature firsthand. His primary antagonist is Yoshikage Kira, a serial killer whose desire for a quiet life directly conflicts with Josuke's mission to protect Morioh's citizens.

Josuke is a Stand user, a manifestation of his fighting spirit named Crazy Diamond. True to his kind heart, Crazy Diamond possesses the extraordinary ability to restore objects or organisms to a previous state, effectively repairing damage and healing injuries. He can use this power to track targets by restoring a severed body part and forcing it to return to its owner, or to trap enemies by fusing them with surrounding objects. However, Crazy Diamond cannot heal Josuke himself, cannot cure illnesses, and cannot retrieve things that have been erased by certain other Stand abilities. Beyond its restorative power, Crazy Diamond is an immensely powerful and swift close-combat Stand. Its physical strength is comparable to Jotaro's Star Platinum, and its punches can exceed speeds of 300 kilometers per hour, making it a formidable weapon in direct confrontation. Throughout the story, Josuke develops from a relatively carefree student into a more responsible and resolute hero, learning to master his abilities and embrace his role as the protector of his cherished hometown.