Red Viper is a muscular snake monster who was hired by Escargoon on behalf of King Dedede (King Dedede was unable to due so because he was left weak from having drank bottles of Power-Down E bought from Nightmare Enterprises) to clobber Kirby in the episode Power Ploy. Red Viper was at an advantage during the battle because Kirby was weak from one of the Power-Down E drinks and was even able to give Kirby a run for his money because of it. His attacks include using his tail as a whip, eating his foes whole, dribbling them, and simply punching them. Tiff and Tuff try to get Kirby away from Red Viper, but he knocks them away and starts using Kirby as a punching bag. Kirby is even unable to board the Warp Star due to his lack of strength. Red Viper then tosses him up into the air and catches him in his mouth. Luckily for Kirby, Chef Kawasaki was able to toss him some homemade stew (made with Pumped-Up D) just before Red Viper's jaws closed down on him. With his energy back, Kirby forces the serpent's jaws open, grabs him by the tail, and slams him around town and into Dedede's limo. After pummeling Red Viper for a bit, Kirby hops on his Warp Star and heads up into space. Red Viper tries to attack Kirby mid-flight in an attempt to free himself, but Kirby evades him, and Red Viper accidentally punches his tail instead. Kirby continues far into space, twirls Red Viper around, and instantly destroys the muscular snake by hurling him into the sun. After destroying Red Viper, Kirby safely lands back down in Cappy Town.
Red Viper is an extremely muscular limbed snake. His body is a large sphere with arms and a tail at the end. He wears a pair of red sunglasses and a tight red muscle shirt. He has a bright green underbelly and a light-brown snout. He has the number eight tattooed on both his biceps and the top of his head, and has a crimson marking running across his back. He growls and hisses like a normal snake would, but is also shown to whimper like a puppy dog after being injured.
Red Viper shares traits primarily with snakes and bodybuilders, but also has some characteristics of canines and basketball players. He may have also been based vaguely off of the Nāga, a group of deities in Hindu culture. Nāgas have an upper body with traits of a human with the lower body of a snake.
Red Viper's English name is a direct translation of its Japanese name, Akamamuji.