|Title||Bufalo Fulmine ver. Vongola|
|Cambio Forma||Lampo's Shield|
|Manga Debut||Chapter 236|
|Anime Debut||Episode 164|
Gyuudon, Lambo's exclusive Box Weapon, was created by remodeling a Lightning Bull. It is imbued with the Vongola's latest technology. Its appearance is that of a big, black bull covered in armor that has the Vongola crest on it. It was the first Vongola Box to be successfully opened, first shown when an angered Lambo used it to get back at Gokudera for his insults.
By further wrapping its body that was solidified with Lightning Flames, it can withstand any kind of physical attack. The offensive power of its horns is tremendous, and that power is demonstrated when it becomes a shield through Cambio Forma.
- Cambio Forma: Lampo's Shield: After Cambio Forma, Gyuudon takes the shape of a helmet with the Lightning symbol on the forehead section and two bladed loops by the sides complete with a shield with horn-like appendages and the Vongola crest with the Roman Numeral 'I' in the middle. With the difference in sizes, Lambo wears the shield around his body instead of carrying it in his arms. By using this weapon, Lambo can perform an electric attack that has a wide area-of-effect called Corna Fulmine (lit. Lightning Horn). A single strike from that technique was enough to destroy Kikyo's army of Nuvola Velociraptor.
- Gyuudon literally means "beef bowl."