Scary Monsters, Part 4 (スケアリー モンスターズ その④ Sukearī Monsutāzu Sono 4), originally Diego Brando, Part 4 (ディエゴ・ブランドー④ Diego Burandō 4) in the UJ release, is the thirty-first chapter of Steel Ball Run and the seven hundred eighty-third chapter of the JoJo's Bizarre Adventure manga.
The guardian of the Eyes whispers to Diego the word "Turbo". Realizing that Diego is being told the location of the next Corpse Part, Johnny shoots at Diego, but the now fully controlled Gyro defends him from Johnny's nails with the Steel Balls.
Dr. Ferdinand, the true master of the dinosaurs and an agent of the government, reveals himself after chastising Johnny for littering, referring to his nails. The geologist reveals, notably, that his employer is the government and that he sent Diego to retrieve the Corpse's left arm. He also reveals that the Corpse is 1900 years old, and that it will bring about an eternal kingdom, to Johnny's denial, who claims that no one could have such influence.
Johnny decides to temporarily abandon his Left Arm and transform into a raptor, using his tail to leap toward Diego and whip the Eyes toward Gyro. Johnny is then incapacitated but Gyro absorbs the Right Eye. He is cured of the transformation and gains a scanning ability which enhances his sight to extraordinary levels. One Steel Ball severely hurts Dr. Ferdinand, who hides among the raptors. Gyro is, however, able to decrypt the vibrations his ball causes and is able to tell in which dinosaur the geologist hides. Johnny shoots him and Ferdinand's power is cancelled. Unfortunately for the latter, he finds himself among cougars who devour him.
The duo also see Diego depart with the Left Eye, having somehow kept his ability to transform into a dinosaur. They now know that Diego will also chase after the Corpse Parts, and resume their race.