After the defeat of the Oni, Wu and his pupils were able to find a period of peace. However, Wu noticed the laziness of his students and sent them out to find a quest. Unfortunately, their new quest brought back another terrible mistake from Wu's past.
Six months after the defeat of the Oni, Wu is left to deal with the Ninja constantly being in a relaxing mood and is utterly incensed by their laziness. The last straw came when the Ninja used the sacred divine bell as a hot tub to relax. Wu angrily confronts them for having done nothing but revel in their victory and becoming out of shape. He has them meet in the monastery where he continues to berate his students. He tells an old tale about the Monks who became Ninja. He then sets loose the chicken that had been used to test the Monks before they could become Ninja. Even though the Ninja defeated it, he set up booby-traps that caught them constantly while they were completely off-guard and henceforth humiliated. When asked to stop, he decided to engage them in battle to show them that they had become unfit and soundly dispatched them all before unleashing the chicken to punish them.
Wu is meditating when Lloyd came in and asked him for advice on how to get back in shape. Wu is outraged by Lloyd's audacity to ask for advice after having been so lazy for months and furiously tells him to find the adventure they would need.
Wu found the Ninja with all their luggage and asked what's going on. They say they were going on a quest, and P.I.X.A.L. mentioned they could test their new vehicles. They both watch as the Ninja left without reading the manual, or bringing their luggage.
Upon learning what happened to the Ninja by Clutch Powers, Nelson and Antonia reach the monastery and tell Wu, who compliments Nelson and said that he reminds him of Lloyd. He tells them to go home and informs P.I.X.A.L. of the situation.
At the Monastery, Wu was in his quarters till Jay, Kai, and Cole came in and tell him that Aspheera is after Garmadon for betraying her and imprisoning her in a Ancient Pyramid for one thousand years, but Wu says that she is looking for him.
Wu flashes back to his childhood back when he was a young child and was playing with Garmadon. They trespassed upon Serpentine land and was taken prisoner by the king, Mambo the Fifth. They are set free after promising a young snake sorceress to teach her Spinjitzu. Wu comes back the next day and teaches her Spinjitzu. She learns it and uses it to betray Mambo the Fifth.
Having recounted from his troubled tale, Wu received backlash from the Ninja for his reckless acts. Unable to explain because of their criticism, Wu took blame for it and before Wu could come up with excuses, they hear an explosion and head outside. When they went out, they caught sight of Aspheera's army approaching the Monastery of Spinjitzu and the Fire Fang spewing fire balls at the Ninja. After ducking from one of the fireballs, Cole asks about the Scroll of Forbidden Spinjitzu's location, and using logic, P.I.X.A.L. thought the second scroll would be with an archeologist, so he contacts Lloyd, Zane, and Nya to find Clutch Powers.
Still trapped inside the Samurai Cave 2.0, he mentioned they need to get the scroll back while Jay, Kai, and P.I.X.A.L. work on the mech.
Wu and P.I.X.A.L. continue to build the Titan Mech. While building, Nya called from the Land Bounty to tell them that she, Lloyd, and Zane have the second Scroll of Forbidden Spinjitzu, and Wu tells Nya to tell Lloyd to be careful with the Scroll and hurry to the Monastery. The Elemental Cobras continue to break down the doors that are close to breaking, the Ninja started to worried but Cole thought of an idea to hide under the vents but P.I.X.A.L. was doing the finishing touches to the mech. A few seconds later, the doors broke down and when Aspheera came in, she saw that the Ninja and Wu was gone, she was surprised at first than later angry, telling Wu to come out and face her if he has the courage but she was alerted when she heard Jay's sneeze, she was able to find the Ninja and Wu. Face to face with her after centuries, Wu heard her state that she always dream of this moment, but was stopped when P.I.X.A.L. came in with the finish Titan mech and kept her away from Wu and the Ninja.
Wu and his pupils engage Aspheera and her forces but soon she was able to overpower him, the Ninja, and P.I.X.A.L. before holding them hostage until Zane arrives in the ShuriCopter and Lloyd and Nya in the Land Bounty. The tides changing Wu watched as most of the ninja used the second Scroll of Forbidden Spinjitzu to engage Aspheera in an epic Forbidden Spinjitzu fight.
In the end, Zane was left to face Aspheera who tried to ignore him and use the power of the Scroll to blast Wu but he dodged, making the Titan mech disappear instead. Zane then used the Scroll to freeze Aspheera and the Pyro Vipers. When Jay questions how Zane was able to do that, Wu replies that it was the power of the Scroll of Forbidden Spinjitzu and asks Zane to give the Scroll to him, Zane hesitated at first but went to give the Scroll to him.
But before Zane could, he noticed Aspheera has manage to break her arm free from the Ice and aim her staff to use one final hit at Wu but Zane saved his master by pushing Wu of the way causing him to be hit instead and be seemingly destroyed. The Ninja, Wu, and P.I.X.A.L. were heartbroken that their friend is gone once more.
After the battle, Wu goes to Kryptarium Prison, where he makes a visit to Aspheera whose powers are currently ineffective and being held in Garmadon's old cell. She remarks on how fitting their meeting is, since it is like her first imprisonment. Wu is infuriated that her vendetta cost him an innocent, one of his pupils and ask if she is satisfied with her deed. Aspheera is confused, as she reveals that she never wanted to destroy Wu but make him feel her suffering by trapping him.
Aspheera goes on by stating Zane was not destroyed but banished to a place Wu would never go to, the Never-Realm, Wu was horrified to learn this and runs out as she taunts him before laughing maniacally.
Heading to the monastery, Wu runs in the room of P.I.X.A.L. where his students are gather and states Zane is still alive, to their surprise. Wu tells the ninja that Aspheera informed him of how she sent Zane to the Never-Realm, a place his father told him to never go.
The Ninja tell Wu they want to join him but refuses to let them come, since the realm is most likely dangerous but they insist to save their comrade. When Wu once more stands his ground, Lloyd seemingly agrees with his uncle's request and tells him to make a plan for his journey before rushing in.
After getting the bag of rations, and a run in with the chicken, Lloyd manages to grab the Travellers' Tea, but Wu had sensed Lloyd despite meditating and rushed to their side, holding Aspheera's staff, under the influence of the Forbidden Spinjitzu. When his demands for the tea were proven inactive, Wu attacks them, but with a distraction from Lloyd, they tie him up and gag him, leaving him overpowered.
Wu attempted to plea to them on stopping but his warnings fell on deaf ears and he is forced to watch in horror as the Land Bounty was teleported to the Never-Realm before being freed by P.I.X.A.L. He bitterly reveals that from the beginning the Tea would never work and he lied to them so he could go alone and resignedly leaves P.I.X.A.L. with a cold condemnation for what she had did, saying that she has sent the Ninja to a place they would most likely never return from.
During Zane's message, Wu appeared in a flashback meditating.
After failing to reach the Never-Realm via Traveler's Tea multiple times, Wu created portals to other realms. He was frustrated in his attempts and added more leaves to try again to reach his students. Unfortunately, a portal to the Departed Realm was opened, and this allowed a mysterious creature to emerge. To Wu's horror, it was The Preeminent that escaped and he watched as it went towards the city. Feeling guilt about letting this threat loose, Wu could only stand sullen until P.I.X.A.L. goes after it.
While P.I.X.A.L. attempts to subdue the Preeminent, Wu states his concerns for her. However, she emerges victorious, he congratulates her on the success.
Later, when the Preeminent has been returned to the Departed Realm, Wu says he would tell the Ninja to not lose hope. P.I.X.A.L. tries to reassure him by saying he needs to trust his words.
A Fragile Hope (Flashback)
When Lloyd notices Zane's Scepter, he gets a flashback of when the Ninja and Wu watches as Aspheera banished him to the Never-Realm.
Lloyd also mentions him in order to get Zane remember him but as his memories were erased he does not remember.
Wu was looking at a picture of the Ninja and P.I.X.A.L. gathered before the Monastery before P.I.X.A.L. alerts him of a strange phenomena that was occurring. Wu then saw the Ninja returning home through a portal. He expressed his happiness to see them again before spotting Zane. Wu gives him a big hug, while the latter is happy to be reunited with him. The old master watched as the delighted P.I.X.A.L. reunited with her companion.