Pepelogoo (ペペログゥ) is a species of small flying creatures introduced in Monster World IV that were believed to have gone extinct, but were rediscovered not long before the events of the game. They are very tame yellow-colored flying animals. Pepelogoo eggs hatch when holy water is applied to them. Blue Pepelogoos also exist, but they are very rare.
Pepelogoos became very popular in Rapadagna City, most habitants having one as a pet. Unknown to them, four wizards planned to spread the Pepelogoos far and wide to have the people's minds under their control, and locked the four spirits to avoid their interference. The exception is a blue Pepelogoo that hatched from an egg Asha found in Rapadagna City's royal palace, which assists in her quest to find the four spirits.
The owners of Pepelogoos start getting in a sour mood, and after Asha rescues the Sun Spirit, the citizens become worse, and Asha witness the yellow Pepelogoos transform into black Pepelogoos. Going to the palace, the Queen attempts to kill Asha by having her Pepelogoo fire a missile at her. However, Asha's blue Pepelogoo takes the hit to protect her, almost dying. Later, after Asha's Pepelogoo recovers, it sings a lullaby that frees the habitants of Monster World from their control and return most Pepelogoos to normal. The people appear to not recall their actions when controlled by the dark magic.
Before the final boss, Asha faces four black Pepelogoos that attack with electricity. They become yellow Pepelogoos again after their defeat. The blue Pepelogoo appears to assist in the battle, covering the eye of the final boss to protect Asha, but being turned into stone. Later, four yellow Pepelogoos (presumably the same ones Asha fought) bring back the blue Pepelogoo to Asha, returning it to normal with the holy water from Rapadagna City's fountain.
A talking blue Pepelogoo appears searching for his friend, a green-haired girl, but as all humans in the Monster World Kingdom were transformed into animals by Nabu, he is unable to find her. He often gets in trouble during his search, but he is helped by Jin, and the kind Pepelogoo also assists him by giving advice. He eventually finds his green-haired friend when the curse is dispelled.
Pepelogoos are small animals able to fly, being able to reach high and narrow places that humans can't. Asha's blue Pepelogoo is very loyal to her, helping by being hold by Asha in order to make her able to glide and double jump, or by letting himself be throw to areas he might help. After being thrown, his actions vary depending of the environment. Those include using its tongue to push buttons or blowing out small flames. Although it tries, the blue Pepelogoo is unable to extinquish large flames. In the Stream Sanctuary, Asha can call Pepelogoo to pull her out of the water before she sinks into the deadly hazards in the bottom. Also, if Asha is carrying a Healing Medicine, Pepelogoo can save her life by giving it to her if she is defeated.
Pepelogoos are very resistant to heat. In the Handera Volcano, the blue Pepelogoo can stay above lava jets to act as a platform to Asha, or block a geyser to push itself and Asha upward. Pepelogoos also have a good nose, Asha's Pepelogoo helping her to find invisible doors in Ice Pyramid 2.
By eating a Pepe Fruit (ペペの実), a red fruit that can be found in the Pepe Tree (ペペの木) behind the temple, the blue Pepelogoo will grown. It grows two times this way, and after its injury against the queen, it grows one more time. Asha is unable to carry Pepelogoo around after its second growth, only hold it to glide and double jump. The last time it grows, it gains arms and a snout, and is able to heal Asha's wounds when she talks with him and sing a soothing melody capable of breaking the dark magic from the four wizards.
The queen's black Pepelogoo assist her in battle, and once was shown to be able to fire a missile from its mouth. The black Pepelogoos that Asha faces in the Underground Fort attack with electricity.
Monster Boy and the Cursed Kingdom contains a blue Pepelogoo that can talk and is able to fire light beams from his mouth, but he must eat ghosts to use the ability.
- "Pikii, pikiiii!" - Yellow Pepelogoos
- "Gee gee..." - Black Pepelogoos
- "Pui, pui!" - Blue Pepelogoo
- The only named Pepelogoos are the first three of the many that the rich woman in Rapadagna City obtains in Monster World IV: Pey (ペーちゃん Pē-chan), Pii (ピーちゃん Pī-chan), and Poo (プーちゃん Pū-chan).