"M", also known as "Horror Mario" or "Mario.EXE", is a sadistic, malevolent entity that haunts video games. Once allied with the demon ex-rock star “Daddy Dearest” to monopolize the gaming industry, he was betrayed and sealed inside a Super Mario Bros. cartridge with his own creations. Thirty years later, “M” sent the cursed game to the outside world, trapping GF and BF inside it, where he took revenge using the power of his Ultra M form