Biff is a recurring character and native alter user.
Biff is technically the first antagonist in the show. Later on, during a strike on HOLY, he gets captured and his abilities are refined immensely. He's also completely brainwashed in the process, to the point that his vocabulary becomes limited to "hammer" and all he can do is take orders, although he is sometimes heard making other noises or words, solely as insults. It is revealed that after being brainwashed, he is completely void of thought, as seen when Asuka Tachibana tried to control his mind. Even the Eternity Extra Shot had no effect on him. He eventually breaks free just before dying, recollecting his name as he falls to his death. He appears in Ch. 42 as one of the people cheering Kazuma & Ryuho on.
NR Hammer (Pre-Refinement): Biff alter ability creates a large mecha that has a gigantic hammer for a right arm with a pair of large round eyes being the only viewable feature on its otherwise bandaged face. "Hammer"'s left arm is disproportionally more massive than its right arm, ending in a great bludgeoning cylinder instead of a hand. Its right hand usually picks up Biff as "Hammer" enters into combat, presumably to keep him out of harm's way from collateral damage, though it provides an additional advantage in viewing a wider scale of the battlefield.
- Piston Hammer: The full-power swing of "Hammer"'s mighty left arm. The pistons on the torso section of "Hammer" pump outwards into view and begin to rotate rapidly, while "Hammer" lifts its hammer-arm carefully into the air (its feet crushing and sinking into the ground from the sheer mass of the limb), before Biff directs it to perform either a forward thrust or a downward smash. Easily capable of collapsing building-sized structures.
NR Hammer (Post-Refinement): After the refinement, Biff's "Hammer" becomes even larger in size, with the previously streamlined physique now converted into a much bulkier, flatter structure. Its face remains virtually unchanged, save for the deep red coloration of the bandages. A small platform rests on the top of the converted "Hammer"'s dome, enabling Biff more space and security to direct his "Alter" in combat. "Hammer" loses its legs in its post-refinement state, replacing them with a giant black cone, capable of functioning as either a spinning top for high velocity across ground or as a drill for excavating holes and tunnel systems.
- Jet Hammer: The post-refinement improvement to "Piston Hammer". Instead of physical engine motion, "Hammer" obtains the force necessary to utilize its hammer-arm by igniting the jet engines located on the top of its left arm, releasing bright purple energy in the process before the hammer is swung at the target. Could briefly clash with a suppressed "Vigorous Left Fist: Garyu" for several seconds before giving way, as well as resist an assault from all 8 "Eternity Eight" orbs.
- Drill Spin: A dual-purpose technique for Biff; he can either apply the rotation of the drill to greatly augment the raw speed of "Hammer" while not sacrificing its mobility across terrain, or choose to tear the rock beneath by applying the drill's energy directly below the "Alter", carving craters or forming tunnel networks for later use.
- Entrenchment: Steel pillars can be fired from holes spaced around the waist section of post-refinement "Hammer", embedding the "Alter" solidly into the terrain. This can either improve the accuracy of its striking force, or intentionally used by Biff to collapse large sections of ground directly beneath.
- Hyper Rematerialization: While not necessarily a trait unique to any one "Alter", post-refinement "Hammer" has an unsually fast reconstitution for such a large and complex structure, especially relative to many other "Alters": it can take Biff up to merely several seconds to fully reform "Hammer" from a completely dispersed state of repair, even from serious attacks by characters many times stronger than Biff himself, such as Ryuhou's "Stage 2 Zetsuei" or "Shell Bullet Ultimate" Kazuma.
- The device seen on his forehead after being refined may be the reason for his mindless state of being and his inability to refuse orders given to him.