While at the Oni Temple with Lloyd, Harumi flashes back to when she was a kid during the events of "Day of the Great Devourer," which was also the day her parents were killed by the Great Devourer.
Meanwhile, the Sons of Garmadon have captured the other Ninja and have seized control of the Destiny's Bounty. With it, the Sons of Garmadon proceed to the Oni Temple.
Back at the temple, Lloyd and Harumi manage to locate the Oni Mask of Hatred within the Oni Temple. Harumi attempts to grab it, but a force makes it so she cannot.
She then explains to Lloyd that someone with Oni blood can obtain the mask. Lloyd was trying to get the mask out but it would only go half way. The baby girl whined in Lloyd's arms and reached out.
"No don't do that" Lloyd said worried that the forcefield would hurt the baby
Her hands went through the forcefield and touched the mask and that allowed the mask to fully come out.
"How did she do that" Harumi mummbled
"Can i see it Lloyd?" Harumi asked reaching towards the mask
Lloyd pulled it a little out of her reach "wait, how did you know i was part oni"
After a moment of realisation, Lloyd discovers Harumi's true intentions.
"Your the quiet one" Lloyd said holding the mask and the baby girl close to him.
A fight then starts, Lloyd vs Harumi, Lloyd dropped the mask near the edge, Harumi dives after it, catching it while she manages to use her knife to hold onto the side of the platform.
Armed with the Oni Mask of Hatred, Harumi puts it on, using its powers to jump back onto the platform.
Lloyd questions what the mask did to her, where she reveals that it has made her invincible to all forms of damage, speaking with a very demonic tone to her voice.
Harumi tells Lloyd that she wants him to feel the pain she has felt following the death of her parents by having Lord Garmadon destroy Lloyd.
"I just need one more thing" Harumi said walking closer to Lloyd
"What else do you want i have nothing else!" Lloyd shouted
"Hand over the baby girl Lloyd" Harumi said
"No way" Lloyd said holding the baby girl close to him
Harumi used the power of the mask to fight Lloyd and get the baby from him, she leaves the temple with the mask and the baby, she used the mask to destroy the temple in an effort to kill Lloyd.
Harumi soon regroups with the newly arrived Sons of Garmadon, where she takes off the Oni Mask of Hatred as Killow rejoices that they now have all three and the baby girl.
Harumi then states they have a ceremony to attend to, ordering the Sons of Garmadon to take the Destiny's Bounty as the baby girl started crying.
They are confronted by the Ninja, who had managed to break free earlier with the help of Toddler Wu and Cole's terrible singing.
Lloyd, using the waterfalls covering the Oni Temple, soon rejoins the Ninja. As the Sons of Garmadon surround them, the Sea Monster that Harumi and Lloyd saw earlier then appears.
The Ninja and the Sons of Garmadon briefly work together to fight the beast, with Mr. E and Killow utilizing the other two Oni Masks to help fight it.
While the Ninja are distracted with fighting the beast, Harumi orders her forces to retreat with the masks. They went aboard the bounty with the baby girl still crying.
"They have Aria!" Jay shouted
"No!" Cole shouted trying to get to the ship, but was stopped by the beast
"What do you mean they have Aria, Aria's gone" Lloyd said
"No Lloyd, the baby boy is Wu so if our analysis is correct then the baby girl must be Aria" Zane answered
"Why didn't you tell me this earlier!" Lloyd shouted
"We didn't know yet! They're gonna get away with Aria if we don't do something!" Jay shouted
Zane made a ice bridge to help Lloyd get up to the bounty. Sadly Lloyd was grabbed by Killow. He fought to get loose, but stopped when Mr. E held a knife to baby Aria's throat.
"No don't hurt her" Lloyd said as he stopped fighting, Harumi laughed holding baby Aria to her.