Koro Koro no Mi

Debuting in the anime's Silver Mine story, this power belongs among the non-canon Paramecia fruits. Its label draws on koro koro, the sound Japanese uses for something tumbling along, and Funimation's dub renders it as the Roll-Roll Fruit. Anyone who consumes it is styled a Rail Car Human, since the transformation replaces the limbs with working train wheels at both the hands and the feet. Aveyron is the one who swallowed it.

Wheels replacing the user's hands and feet spin at will, letting the holder charge forward and knock people over through raw momentum. Because those wheels lock onto rail lines, riding along track is possible anywhere it runs, and staying mobile on just two wheels frees the remaining limbs to strike. The same spinning motion can drive separate gear, drills among them. Braking, however, is the catch: stopping proves difficult, so a whiffed charge leaves the holder exposed, and reaching severed track flings them skyward rather than halting them. Beyond that, submersion in water and the other usual Devil Fruit vulnerabilities still bind the user.

Aveyron keeps the fruit running around the clock to move through the tunnels beneath Silver Mine. A rear compartment stores his arsenal, from bombs to a drill to spare cannon parts he bolts onto his frame, and he charges enemies by ramming them at speed. His Bakudan Ame technique, called Rain of Bombs in the Funimation cut, has him roll a track on wheeled feet while flinging a mass of explosives ahead to shower his foes, first deployed against Luffy, Bartolomeo, and Desire. With Hyper Special Express he bolts an assortment of gear onto his cart's frame, including cannons, a fresh engine, drums of oil, and a hammer of silver, gaining greater speed and firepower. That wheel motif draws comparison to two other rolling powers, namely the Guru Guru no Mi as well as the Shari Shari no Mi.