The Bonnes constructed Bruno in a large warehouse of the Old City area of Kattelox Island after Mega Man Volnutt destroys the Bonnes' Gesellschaft. They drained energy from the nearby power plant to help in its construction, and during the Bonne's stay in the Old City, people comment they hear strange noises in the local, and some believed there where ghosts in the city. After opening the Sub-Cities, Mega Man meets the Bonne's in the warehouse, as Tron Bonne yells at him over her near death experience after Mega Man shot down the Focke-Wulf, but Mega Man is just happy to see they're alive and shakes a flustered Tron, catching Tron off guard. Teisel Bonne turns the corner and, enraged, starts the machine, attacking Mega Man after destroying the building they are in. MegaMan manages to destroy Bruno, which broke in half before exploding, but spares the Bonnes.
Bruno attacks with a wide arsenal of weapons - the Bonnes' cannon beam or green energy orb on each arm, the barrage of gattling guns on each leg, as well as several grenade launchers on its legs and shoulders which are capable of hitting MegaMan from any distance. Bruno is also capable of ramming through any obstacles, bringing down even buildings on its path.
- Height: 43.5 m
- Width: 21.7 m
- Total amount of muzzles: 34 gates
- Weight: 53 t
- In-game, Bruno has the longest health bar among the game's boss - surpassing MegaMan Juno's two modules (the final bosses of the game). But Bruno's armor is not as durable, which cause its health bar to go down quite fast.
- Theodore Bruno roughly translates to "Armour of God"