Mario has the typical look of a Salaryman. Average height, black hair combed and smoothed down, and wears plain office clothes. With his eyes shut all the time, Mario looks at first sight as a quiet and spiritless person, although this is to hide his true personality, because when he opens them, Mario's eyes seem unusual, even manic, which along with his long tongue gives it a creepy appearance.
After taking Trigger, his body transforms. In addition to increasing size to be as large as a tall building, he grows a pair extra arms and his skin turns jet black. He also has no body hair, and his facial features acquires a simpler appearance.
Mario appears to be a very timid and easily spooked individual. When Knuckleduster approaches him while yelling, he is very easily intimidated by the Vigilante. He also is very apologetic, apologizing when he drops his suitcase and reveals the toys inside.
However, this is revealed to be an act to get away from the Vigilantes and Heroes. He is revealed to be a person who preys on people who have either a weak will or fragile pride and offers them the drug Trigger in order to make them go berserk with their Quirks. He displays a sinister side to his personality, showing some kind of perverse obsession with toys and the drug itself.
When under the effects of the drug, Mario regresses into a childlike state, contradicting his Quirk's appearance. He begins to play cars, and anyone whom he is able to grab hold of, like they were toy airplanes, even making the sound effects as he does so. He appears to regress mentally back to being a child completely.
Mario is very crafty and proved a skilled liar by convincing the authorities that he was just another unwilling Instant Villain - allowing him to be released back into the public free of charge.
Quirk and Abilities
Unnamed Gigantification Quirk: Mario's Quirk is only seen under the effects of the drug Trigger. However, when it is seen, it turns his body completely black, increases his height to a colossal size, and gives him four arms.