It is a giant black motorcycle with three wheels and the armored head of a rhino. It is very powerful, capable of barreling through multiple enemies, and with sufficient momentum, it managed to topple Big Mom. It has the trademark star on the two back wheels. It is made of Wapometal and can "dock" with the Brachio Tank V to form the Iron Pirate General Franky.
Fish-Man Island Arc
When the New Fish-Man Pirates' Hyper Toxin Squadron tried to poison Nico Robin, Franky drove the motorcycle out to run down the squadron, having immunity from the pricks and poison. A giant fish-man tried to smash Franky and the bike with a giant flail, but was taken down by another new addition to the Soldier Dock, the Brachio Tank V. After both vehicles were caught in a pitfall made by Daruma, Franky took them both over, and "docked" them to form Iron Pirate General Franky.
Wano Country Arc
When the Straw Hats Pirates disembarked on Onigashima during the raid on Kaido, Franky drove the Kurosai FR-U IV with Brook riding on it. When the two later arrived on the Live State, Franky ran over Big Mom's face with the back wheel of the motorcycle.
- The name FR-U means General Franky no Ude (フランキー将軍の腕 Furankī Shōgun no Ude?, literally meaning "General Franky's Arms").
- One Piece Manga and Anime — Vol. 64 Chapter 635 (p. 13-15) and Episode 556, Franky reveals the Kurosai FR-U IV against the New Fish-Man Pirates.
- One Piece Manga and Anime — Vol. 64 Chapter 636 (p. 4-6) and Episode 557, The Kurosai FR-U IV and the Brachio Tank V form "General Franky."
- One Piece Manga — Vol. 97 Chapter 979 (p. 6-8), Franky and Brook ride the Kurosai FR-U IV on Onigashima.
- One Piece Manga — Vol. 98 Chapter 988 (p. 14-15), Franky ran over Big Mom's face with the Kurosai FR-U IV's back wheel.
- One Piece Manga — Vol. 98 Chapter 989 (p. 15-17).
- Black Rhinoceros – Wikipedia article about black rhinoceros.