Mamanu is the former Royal Enchantress of Hakalo. She was caught stealing magical stones from the Royal Museum and was banished from Hakalo by Lani's father. She came back to take revenge against the Royal Family of Hakalo by stealing the Emerald Key of Hakalo so she could leave the Royal Family lost at sea and take over Hakalo. She was stopped by Princess Lani and knocked into the sea.
She resurfaced in Enchancia and decided to disguise herself as Lani in an attempt to get the Emerald Key. She appeared at the castle, claiming that the real Lani was a fake, so King Roland II decided to test the girls. She won the first test by dancing the waltz, but failed the present test after an outburst of anger over a snail. She tried to make it up and failed, so she put a spell on the bed that Lani was sleeping in so Lani could be too tired to win the final test.
For the final test, she and Lani had to get out of a maze by using their intelligence. She won the final test because of her cheating and made off with the Key. However, Sofia and her family soon discovered this fact and chased after her. She was stopped by the animals of the forest, Lani, Sofia and her family. As Roland ordered his guards to seize her, she escaped with the same stone that she had used for the disguise and swore they had not seen the last of her.
Mamanu returns in "Stormy Lani", somehow finding a way to get back on the Island of Hakalo. She summons her minion snake, Milo, and sets out to ruin Lani's Fire Pearl Quest, hoping to have Lani lose control of her temper and unleash a devastating storm to destroy Hakalo. She was successful in getting Lani to lose her temper several times, only to thwarted by Sofia, who kept calming Lani down. When her minion failed her, Mamanu turned him to stone, stole the Fire Pearl, tossed it into the volcano, and taunted Lani, hoping the princess would finally lose her temper all the way. Instead, Mamanu was surprised by Lani's control and was sent flying off the island due to the princess's new fire power. What happened to Mamanu after that is currently unknown.
She is the second villain in the series who tries to take over a kingdom by using a magical object (Emerald Key) that belong to the kingdom's royal family. The first is Cedric by using Sofia's Amulet, however, Mamanu stole the key successfully while Cedric keeps failing to gain possession of the Amulet.
It's shown many times that Mamanu has an aversion to animals.
Strangely enough, she uses her disguising necklace to turn into different people and animals a lot and her minion is also a snake.
"Princess Lei-Lani" was the first disguise seen in "The Emerald Key", later into miscellaneous animals in "Stormy Lani"
She is also the second villain to be defeated by being thrown into the water, the first being Cedric in "The Floating Palace".