Keko and Piyo are mother and child types of birds. Keko is the mom and Piyo is the son. They appear in Cloudy Park. (Level 4-2)
Very, very close to the end you will see Piyo in a balloon trying to fall but too scared. Keko wants her son back so Kirby (or Gooey) need the Needle ability to pop the balloon and Piyo will fall. When he touches the floor he will do a move like saying "Hi" or "Bravo". Then enter the next door and Keko will give you a Heart Star.