Jackie and Jade, in a mini sub, find the last Oni mask at the bottom of ocean. However, Jade is suspicious, as usually, Tarakudo and his goons would show up, in which they would do the ultimate good vs. evil battle royale; Jackie is relieved. However, as they make their way back to Section 13, their stream of bubbles reveals Tarakudo, smiling evilly.
At the vault, all nine masks are secured and the Chans believe their quest is complete. Then suddenly, Tohru had the willies, as the masks glow and shatter, releasing the Oni generals from within. Led by Ikazuki, they leap at the Chans but Jade uses the Dragon Talisman to repel them. As she gathers the rest, they escape and lock the Oni in the vault. But they summon one of each Shadowkhan to attack the Chans, which they all destroy with the Talismans. But when the ninth, the mantis appears, they use the Snake talisman to get out of the compound. But even outside, countless Shadowkhan are everywhere. But then they merge into a shadow shroud, covering everything in darkness. As Tohru recites, the combined power of the masks can summon enough Shadowkhan to cover the Earth in eternal darkness.
At the shop, Uncle erects a spell to protect the shop from darkness. Tohru is confused, as he had memorized the legend. But Jade finds a convenient piece that they've accidentally flipped over. It says that the masks shouldn't all be brought into one location, which is why they were scattered across the Earth. But even worse, the darkness will eventually erode all good magics to nothing. Just then, someone knocks at the door, but it turns out to be Viper and El Toro. As they are filled in on the current events, Jackie begins to elaborate on the spell ingredients that originally defeated the Oni but Uncle whacks him, informing everyone that the spells were to only work on the masks, which are now destroyed. Their only hope is to defeat Tarakudo. Captain Black calls, having evacuated Section 13 and operating from a mobile unit. They had monitored the Oni, going in the directions of the compass, in pairs to spread the shadow shroud. The J-Team splits up, empowered by the Talismans, to take down the Oni. Jackie refuses to bring Jade along, as he would not live with himself if something happened to her. But she disregards orders, using the Rat to animate Super Moose. However, Tarakudo picks up their interference form Section 13 (which had its onion odour removed), and one by one, took down the J-Team and imprisoned them in Section 13.
While trying to escape, Jade casually throws away the Hana Fuda cards she kept in her bag, which reveal the existence of Tarakudo's mask, which he hid in the Shadow Realm. The only way to get there is through the shadows and the usage of dark magic, by replicating the image of Tarakudo on someone. Jade volunteers to become Queen of the Shadowkhan again but Jackie says no. Uncle volunteers Tohru, telling him that he must face his fears and puts the image of Tarakudo on him. Nervously, Tohru tells ninja Shadowkhan to take him to the Shadow Realm, maintaining a way back to the living with Uncle's magic sock. He finds the mask but when he gets out, he has a quick transformation to evil and calls for Tarakudo, who answers his summons. Upon noticing the mask, Tarakudo attempts to destroy it, causing the J-Team to fall into the parking lot beneath. As they recover, Tarakudo calls upon Ikazuki to aid him, only for the Oni general to be tackled by both Viper and El Toro. Uncle shouts from atop a pipe that he needs the mask ingredient, hair of Japanese samurai. The only problem is that ancient Japan, is ancient history. Believing that Tohru may be a descendant, the J-Team gets a small bit of his hair and get it to Uncle. The moment he drops the hair into his potion, there is a blinding flash of light that affect Tarakudo, causing him to fall to the floor. As the smoke clears, it is revealed that the spell has granted Tarakudo a physical form, necessary for mask to stick to face. But even without his mental powers, he is an able fighter, who easily defeats the J-Team. He then goes over to Jackie, demanding his mask, only to find out that he doesn't have it; Jade does. She slaps it on his face, which causes the Oni and shadow shroud to be sucked within the mask, including the tattoo on Tohru. Tohru inquiries if their mission is really over, to which Uncle points out that if he doesn't have the willies, then there are no more masks.
- Despite being warned in The Masks of the Shadowkhan, Jackie and the gang still gather all 9 masks in one place.
- This episode features the last appearance of the Shadowkhan in the series, though they still appear in the Season 5 opening.