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3UP Mario (3UP マリオ), also referred to as Moon Mario (ムーン マリオ), is a form Mario assumes exclusively in Super Mario-kun. It is acquired when Mario collects a 3-Up Moon, which would instead grant him three extra lives in Super Mario World.
In this form, Mario gains a crescent moon on his cap. Whereas Moon Mario has a large moon centered on his hat's "M", 3UP Mario's moon is more inclined, smaller, and can be detached and thrown at enemies.
In volume 2 chapter 2, Mario becomes Moon Mario and uses this form to defat the Mekakuppa via using invincibility against the robot's lasers and taking a Cape Feather from the Item Storage, which he then uses to tickle the Mekakuppa to death.
In volume 3 chapter 3, Mario grabs the 3-Up Moon and becomes 3UP Mario to defeat Metto Oyakata with a fire kick, launching it into the powder magazine and exploding the entire underground in the process.
In volume 6 chapter 10, Ultra Pukupuku sends Mario flying into a rock, where he finds a 3-Up Moon, becomes 3UP Mario, and uses the moon as a fishing hook and a lightning rod as the wire to trap Ultra Pukupuku and shrink it, thereby defeating it.
In volume 12, another 3UP Mario variation appears. This time, it is not a transformation derived from the 3-Up Moon, but by obtaining three extra lives from the Donkey Kong slot machine. With this, Mario summons three clones of himself.
In volume 47 chapter 4, Mini Mario is tossed against a wall by the enlarged Boom Boom. In the wall, Mario finds a 3-Up Moon and uses it to defeat Boom Boom using the Moon on his cap to hit and shrink him.