Gyro Zeppeli

Gyro Zeppeli (ジャイロ・ツェペリ) is a fictional character from the Japanese manga JoJo's Bizarre Adventure. In Steel Ball Run's alternate universe version of the world, he most likely takes the place of William Antonio Zeppeli, Caesar Antonio Zeppeli or another previously unseen member of the Zeppeli family. He is the main character of this series alongside Johnny Joestar.

Personality
Gyro has a cocky and flamboyant personality, appearing to have a high opinion of himself. However, he can be driven by emotions for other people and become realistic and serious when a problem presents itself. Like most Manga archetypes, Gyro is incredibly intelligent when he needs to be. His most distinguishable body features are his long hair, western hat and his teeth which have "GO! GO! ZEPPELI" written on them, revealed whenever he smiles at someone. His signature laugh/chuckle is "Nyo ho ho ho~".

Gyro's Past
Gyro is from the Zeppeli family, a line of practised executioners in Italy. They use an ancestral technique named the 'Spin' which allows people to die painlessly, usually applied through the use of an iron ball. Gyro lived this way until his late teens, becoming a skilled executioner. However, this is not to say that Gyro kills indiscriminately. Although the Zeppeli family usually sticks to delivering the death penalty to serious and dangerous criminals, there was one incident which resulted in the arrest and death sentence of an innocent little boy who made a living from cleaning shoes, Gyro was struck when he heard of this and even more when the boy offered to clean his own executioner's shoes. Gyro's father is strictly convinced that the Zeppeli family are in the hands of the state and they aren't the ones who choose whether or not someone dies-- refusing this, Gyro pleads with the king for an appeal. After this, it's agreed that Gyro will receive an amnesty to release the boy if he can complete the American cross-country race, the Steel Ball Run.

Johnny Joestar
Shortly after joining the race and before it begins, he fights with a man, using his 'Spin' and iron balls as weapons. During the conflict, the paraplegic Johnny Joestar touches one of Gyro's spinning balls which causes his paralysed legs to move for a moment. Gyro convinces Johnny that it was simply a reflex of his legs but Johnny isn't convinced and joins the Steel Ball Run race to follow him.

The 'Spin'
The 'Spin' is the Steel Ball Run counterpart to 'Hamon' used by the Zeppelis in Jojo's Bizarre Adventure.

The Zeppeli family's 'Spin' technique is Gyro's primary means of attack. The iron balls which Gyro carries are his weapons which he uses the 'Spin' technique with. By throwing them, he seems to be able to control their path, cause spiral ripples in the flesh of his opponents and even return to him once it's done.

The Golden Rectangle
The actual technique behind the 'Spin' is through the mathematical Golden Rectangle. If you continuously divide the rectangle, the angle which connects the corners of each rectangle will form a spinning motion. By aiming at this point clockwise, any thrown object can achieve the 'Spin' and cause a rippling motion in the flesh or surface of any person or object. The Golden Rectangle can be found in nature and requires a reference in order to be used, therefore rendering it useless in an empty room or vast flat ground.

Scan
Once Gyro receives one of the Turbo eyes from the battle with Dr. Ferdinand, he gains the Stand 'Scan', which makes an eye appear on his iron balls. This empowers the spinning motion of the balls and allows him to see through people's bodies like an X-ray, allowing him to aim at specific points for higher damage.

At the series' current position, he no longer has this Stand, after having given the eye to Lucy Steel.

Other Media
Gyro Zeppeli was featured in the Nintendo DS game, Jump Ultimate Stars as a support character.