|“Who are you?”|
“Just an old woman who has made a great many mistakes. That's how I got my name—Mistaké.”
|— Lloyd and Mistaké, Iron & Stone|
Mistaké (alternatively spelled as Mystakе) was an ancient Oni disguised as an elderly woman, who owned a tea shop within Ninjago City. Mistaké once lived in the First Realm alongside her fellow Oni, and was later dispatched to kill the First Spinjitzu Master—but after seeing the beauty in the realm he created, she changed her ways. Over the years, Mistaké witnessed much of Ninjago's history, including the end of the Serpentine War. She was acquainted with Wu, a son of the First Spinitzu Master, and occasionally provided him and others with various types of tea with special powers.
When the Sons of Garmadon sought to resurrect Lord Garmadon, Mistaké provided the Ninja with knowledge about the Oni and dragons. She later helped save Lloyd after his nearly-fatal battle with his father, and motivated him to lead the Resistance after his friends were seemingly killed. During an attempt to seize Garmadon's power, Mistaké revealed her true Oni form and battled the dark lord. She was ultimately overpowered and killed, though her actions helped the Ninja claim victory.
Mistaké once lived in the Realm of Oni and Dragons before the First Spinjitzu Master fled to build Ninjago. She was among the Oni set out to either extradite or kill him. But Mistaké had a change of heart upon discovering that Ninjago was beautiful, and refused to carry out her orders. She decided to stay in Ninjago as a result, staying undiscovered throughout the millennia by disguising herself with her shapeshifting powers. She has helped the First Spinjitzu Master and his descendants ever since.
Following the end of the Serpentine Wars, Mistaké was part of the council that ordered the banishment of the Anacondrai generals to the Cursed Realm. When Arcturus begged for mercy, Mistaké claims she has never heard of it.
Master Wu visited her shop, requesting Traveler's Tea. At first she claimed not to have heard of it, but upon receiving payment, she brought the tea out from behind the counter, warning him of the consequences before Wu tells her he will not bother her again.
Lord Garmadon entered Mistaké's shop, asking for Traveler's Tea. She told him that only a fool would request the tea, but after recognizing him and realizing that his request was serious, she changed her mind and went to retrieve some from the back of the shop.
When the Ninja were reduced to children and menaced by a resurrected Grundle, Master Wu and Nya went to Mistaké's shop with a request for a special tea, which she replied that they are all special and calls Wu an old fool before Nya refers to what Mistaké knows is Tomorrow's Tea. When she went to check her supply in the back, she was unable to pinpoint the tea's location. As a result, Nya and Master Wu were forced to rush to the Ninjas' aid upon finally retrieving Tomorrow's Tea.
Present Wu informed the past Elemental Masters to find her and drink Obscuri-Tea to forget the return of the Time Twins.
Lloyd, Jay, Zane, and Cole visited Mistaké's Tea Shop for the Tea of Truth to loosen Luke Cunningham's tongue. At first, she tried to claim not knowing her own name, but upon seeing Lloyd, she apologized for her rudeness because she didn't recognise his voice. Knowing they were after the tea, she goes in the back, warning them that the truth can be dangerous beforehand. Upon seeing a painting, Mistaké said it is the Oni and the Dragon. While Cole and Zane left with the tea, Lloyd and Jay stayed behind to listen to Mistaké's story about the Oni and the Dragon after she gave them the Tea of Enlightenment to visualize it. She also warns Lloyd not to let the three Oni Masks unite as they will resurrect Lord Garmadon, not as the same man that was his father, but a soulless being.
Wu told Misako to tell the Ninja to take Lloyd to Mistaké's Tea Shop after he was injured in the fight against Garmadon. She makes a tea that comes with a consequence as the Ninja place their hands on Lloyd before having him drink it. It was revealed they didn't lose their powers, but Lloyd did. Before they left to fight the Colossus, Mistaké gave them a packet "to go," which is later revealed to be Traveler's Tea. Lloyd later woke up after seeing a vision that Garmadon would be after Wu and as he and Nya leave, Mistaké gives Lloyd a parachute in a tiny bag, giving him advice that what to do and when to do it is what gives him power. She then explains that this battle wasn't the end, but rather a new beginning.
Skylor told Lloyd that Mistaké told her about where they were and needed assistance. Later, she and Lloyd have tea where she tells him where his friends are and reveals her name is not "Mistaké" and only got it because she made many mistakes in the past.
Mistaké watches Lloyd's speech on TV with his mother and the other Resistance members.
Dareth bugs Mistaké into giving him a tea which will give him power before she gives in. She makes the tea which the jug was about Dareth's height and he starts drinking it. The moment he finished, his hand started bursting brown, but left a side effect of him needing to relieve himself.
When the Sons of Garmadon raid the base, Killow tells Luke to grab Mistaké, but when he came into the room, she had disappeared, and a rat passed by. Later, the rat came up to Lloyd, Nya, Skylor, and Dareth, the latter scared by its presence before it reveals itself to be Mistaké. She tells them she will explain after she has eaten.
After eating, Mistaké finally explains her origins as an Oni to Lloyd, Nya, Dareth, and Skylor. She explains she has lived so long because of her Oni blood (and that Wu and Garmadon have also lived long due to this) and has the ability to transform. When Lloyd asked why he can't transform, she replied he already had, from the bratty boy to the destined Green Ninja.
Harumi informed the Resistance that the Sons of Garmadon would find her. Mistaké and Skylor comes in carrying the Oni Mask of Hatred. Lloyd refused to use it. On the rooftop, the Resistance thought of a plan to use Skylor as a prisoner and Mistaké would transform into Harumi. They could get close enough to Garmadon so Skylor can copy his Elemental Power to control the Colossus.
They set their plan into action, but Garmadon was suspicious when they noticed "Harumi" didn't add that Skylor can copy Elemental Powers. They were interrupted when the real Harumi approaches them.
After taking Skylor to Garmadon and being captured, she turns into her true Oni form and battles Garmadon, which allows Skylor to touch Garmadon and gain his power. After battling Garmadon and letting Skylor escape, Garmadon demands that she surrender. She defiantly exclaims her catchphrase, claiming she never heard of the word, and summons a staff to strike Garmadon. Garmadon catches the staff and stares at her menacingly, telling her she had made her last mistake. She was killed by him off-screen.
Mistaké was somewhat impolite but kind to some people, like Lloyd. She pretended not to have or know things like Traveler's Tea, but after having been paid or having recognized people she knows, she either gave warnings about the teas she sold or gives advice. She was said to have made mistakes in the past, hence her chosen name. Because she had learned from her mistakes, she possessed a wisdom that rivaled Master Wu's
- Her nickname is a play on the word "mistake."
- In her first appearance, there was a child with her when Wu came to purchase Traveler's Tea. It is unknown if the child is a neighbor she was babysitting or someone who just worked at her shop.
- She is the second person to remark Lloyd's voice change in Season 8; the first is Cole.
- As she was one of the Oni who followed the First Spinjitzu Master, she was one of the oldest, still living characters in the series, being thousands of years old.
- It is unknown why she had not used her powers prior to Season 9 to help the Ninja, since she was an Oni. It is possible that she would have been discriminated by others if she had revealed herself to the public.
- In the episode "Green Destiny," an old woman that looks like her was shown to be in a pick-up truck with a few other people. This may have been simply the animators using her model for a random bystander.
- She is the first major female character to die in the series. P.I.X.A.L. and Nya's deaths are removed thanks to Jay's last wish.
- Only one minifigure of her was ever made. This minifigure came in The LEGO Ninjago Movie set, The Dockyards. There are only two noticeable differences between the two: the movie version has glasses and does not wear a Vietnamese hat.