Captain Illu is Lula's twin sister. She was born with the power of illusions, hence the name "Illu" (short for illusion).
Later in her life, she was giving an item called the Sword of the Mist by Sing, the good guardian of Justice and Injustice world. Sword of the Mist has the ability to make illusions; most common is the illusion of one's fear. She's a captain with her own crew stealing treasure. Now, she stays in The AnimeLand. She bears a grudge against Noah due to the fact that he now has the ability to make illusions as good as her.
When she was 12, her, Lula and Tee, went to different worlds. Captain Illu went to the Village Hidden in the Mist and learned a very secret jutsu known as Dead Man Jutsu which nobody knows due to the fact that it was invented by there great-great-grandfather (who says "it got it's name from the day I made it" because it was made the day he died, hence the name "Dead Man's Jutsu). Unlike her sister, Lula, Illu does not like getting help from people and is used to getting help from herself. Inside her sword is the dagger of the mist which can hurt or paralyze somebody but if the dagger is damaged, whoever the dagger cuts, no matter how many species, will die.
There are certain occasions that the species won't die (example: sight was enchanted by the Temple of the Tiger, which was granted tiger invincibility as long as he's in tiger form). In one episode "The Spider and the Mist", it was revealed that anybody who gets bitten by Kumu and gets ejected with her poison is immune to the dagger. Like her sister, Illu has problems when people are getting too close to her, only when she is furious of loving a game. In the episode, "The Last Phoenix's Ashes", it was revealed that the feather on her captain's cap is the phoenix feather, however, in order for it not to be turned into ashes, half of it had to be fused with a griffin's feather. It was given to her as a reward for saving her captain's old parrot who turned out to be a griffin, itself.