Radio Gaga is a long serpentine creature that disguises itself as a guard rail. Its skin is hard, dry and firm, similar to an iron plate. It has eyes resembling screws, with a thin slit in between them.
Radio Gaga is malevolent, as it disguises itself as a guard rail and lures in victims such as birds and other animals. It's also shown reprimanding Lucy and Joseph for abandoning their seemingly dead driver, calling them low-lives and their actions inhumane. Lucy compares the creature to be similar to a snake or guard dog. The creature is shown to have a cowardly side, as it decides to flee after being beaten up by Joseph Joestar and his Stand.
The creature frequently makes rather unintelligible sounds, such as "ga ga" (ガガ).
Radio Gaga is capable of luring in potential victims by mimicking its previous victims' voice, by vibrating its own body surface like a speaker. This ability helps Radio Gaga hunt for food, such as birds and other animals. Any human who is lured near the guard rail seems to act strange, such as muttering "ga ga" or taking off their clothes. Once the victim is near it, Radio Gaga then sucks them between the steel plates and crushes and digests them.
Radio Gaga is capable of controlling the bodies of its crushed victims. The bodies are noted to be barely kept alive. The controlled body is seemingly held by its intestines that stick out from the guard rail's gaps where it crushes its victims. From this, Radio Gaga can mimic human voices. It also uses the body-puppet to extend its grasp and drag in potential victims.
Although its origins are unknown, Radio Gaga is heavily implied to be Toru's "guard dog", as it lived near the Twin Pines, where Toru would at some point be spotted planting Locacaca fruits. At some point, the creature was responsible for the disappearance of a woman, having lured and devoured her, though it's implied that it claimed more human lives. The disappearance of the woman was dubbed the "Radio Gaga Incident" (ラヂオ・ガガ事件 Rajio Gaga Jiken), making the spot it inhabited famous.
During her time in Morioh, Lucy Steel investigates the location of the orchard where the creature lies, and encounters a young man named Fumi. She hires Fumi as a local guide to the orchard, despite his warnings. As they investigate the Morioh Hunting Grounds, Radio Gaga mimics a human voice to lure in their driver. Lucy and Joseph watch as the driver walks towards it and strips himself naked. Then, as a truck passes by, the creature swiftly snatches the driver and crushes him between its plates.
Next, Radio Gaga lures Lucy towards it. It then snatches Lucy's shirt and tries to pull her in. However, Joseph intervenes, throwing his geta between Gaga's plates to prevent it from crushing Lucy's arm, and then pulling her out. Joseph then carries Lucy, who is suffering from a lung disease, to the driver's car.
However, Radio Gaga uses the driver's body as a puppet and grabs Lucy by the neck. Via the corpse, the creature reprimands Lucy and Joseph for leaving their driver behind. Joseph tries punching the body-puppet away, but the guard rail creature ensnares him by the neck and tries to drag him in. However, Joseph throws his geta sandal at the car trunk and grabs an electrical cord. He then unleashes his Stand ability and produces vines around the cord to turn the car to ignition. Then Joseph makes the car run forward and ram into the guard rail. Gaga now vulnerable, Joseph uses his Stand to pummel it, causing it to break off. Joseph and Lucy then flee, and Radio Gaga, on the ground and now frightened, also decides to flee and slithers away into the tall grass.