It’s called Steel Ball Run because that’s the name of the cross-country horse race at the center of Part 7, and the manga is named after that event. In-story, the “steel balls” refer to Gyro Zeppeli’s signature weapon, while “run” points to the race itself.

Why the title fits

The title works on two levels:

  • The race is literally the Steel Ball Run.
  • The phrase also ties into Gyro’s steel balls, which are important to the plot and to Johnny’s journey.

Extra context

The story’s race was organized as a huge publicity event across America, so naming the part after the race makes sense as a headline title. Fans also often read the name as a punchy, stylized title choice by Araki, which fits JoJo’s tendency toward dramatic and unusual naming.

In plain terms

So the simplest answer is: it’s called Steel Ball Run because the race is the story’s main event, and the “steel balls” are a major recurring symbol and weapon in the part.