A seemingly redeemed Harumi learns she is pregnant with Lloyd's child just before his death, and decided to use it to her advantage. 20 years later, her son is proclaimed her loyal assassin and must eliminate Green Legacy, a rebel group run by Garmadon himself, who want to overthrow Harumi, who is now the Empress of Ninjago. But,

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Trailer

Harumi was lying in a hospital bed with Lloyd and the Commissioner looking through a window. "I used your father just so I could revive his own." Harumi spoke to someone. "And when I was found, almost everyone pretended that the whole thing with your grandfather didn't happen." 

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Harumi, with an ankle bracelet on, along with Dragon and Misako watch as the Destiny's Bounty return from their failed attempt to stop the Oni. "When the Oni came, he wouldn't let me fight with him."

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A few hours later, after the Tornado of Creation, the Ninja find Lloyd under some rubble, unresponsive. "I guess he somehow knew."

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Harumi was now in an alleyway, having fled out of anger for her boyfriend's death, and looks at a pregnancy stick. "And now that you're here, you will help me avenge him." Harumi drops the stick next to her ankle bracelet that she took off.

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20 years later, an older Harumi, in ceremonial robes, faces a young man with white hair and green eyes, who kneels before her while Ultra Violet and Killow stood behind him. "I will make sure they pay for killing my father, my Empress." The young man replied before standing up.

"You have been trained well, Don."

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Don holds a helmet in his hands before turning it around and places it over his head. "Now, use it to your advantage." Don puts the helmet on.

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In an underground bunker, Garmadon was facing three young men, a woman and a Nindroid. "You're all still in training, which is why I sent your parents to look for this individual." He said, pointing to an image of Don with his helmet on. "No one knows who he is... but I have a feeling that he is part Oni."

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Don, who lost his helmet during his fight with Jay, clashes swords with him. "Those eyes." He said. "They were your father's. Don't listen to what Empress Harumi said. We didn't kill your father."

"Shut up!" He yelled, kicking Jay back before conjuring some Energy in his hands and fired it at him, striking the left side of his face.

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Don, wearing Vengestone cuffs, sits in a cell as Garmadon faces him. "Your mother used me to try and kill your father, but he saved me." He spoke to his glaring grandson. "He sacrificed his life to save Ninjago. The Oni were the ones that killed him, not us. We need you."

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Don faces Garmadon's five students, who were shocked to see him. "So, I guess I'm your new leader." He awkwardly said.

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Don strikes Ultra Violet down. "I don't know if I can be the leader of the New Generation of Ninja." Don spoke to someone. "I almost killed Jay, took Zane's legs, and put Cole in a coma."

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Kai was facing Don, who overlooks Ninjago City before lowering his head. "Your father was once the same." He said before placing a hand on his shoulder. "So was I. Besides, Ninja never quit."

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The Green Ninja waves his sword to the side to block a Green Legacy member's sword before firing a flow of Energy at another member, the Navy Ninja fires a flow of Water at Ultra Violet, the White Ninja fires a flow of Ice before the Blue Ninja slide along it to fire Lightning, the Red Ninja fires a trail of Fire, and the Black Ninja slams the ground, causing pillars to rise up.

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The Navy Ninja and a girl a little older than him briefly kiss.

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Harumi lies on the ground as her son faces her. "Why did you betray me?" She asked.

Don just glared at her. "The best way to defeat your enemy... is to make them your friend." He replied before raising his sword high.