Dagon/Synopsis

Fearsome Womb Arc
Dagon accompanied Jogo and Hanami to a meeting with Geto. Dagon sits next to Hanami, while Jogo and Geto discuss their plans.

Later Dagon uses his Domain Expansion within an apartment, and relaxes in the water while Mahito sits on the beach. When Geto arrives, he comments about how Dagon has quite the calm domain.

Vs. Mahito Arc
Dagon is mentioned by Mahito, who talks to Junpei about cursed spirits and cursed energy.

Shibuya Incident Arc
Before October 31, Dagon is playing with Hanami and Mahito while Geto and Jogo discuss their plan to seal Satoru Gojo.

On October 31, Dagon is with Geto while Hanami, Jogo, and Choso deal with Gojo. Once Gojo is sealed, Dagon joins the others. When it is revealed that Gojo has been sealed and that sorcerers would be coming to their location, Dagon joins in when they decide to combat the sorcerers. Before splitting up, Dagon eats a large amount of humans.

Dagon is waiting behind a pillar when he runs into Kento Nanami, Maki Zenin, and Naobito Zenin. Naobito easily manages to capture Dagon and lands a devastating blow that forces Dagon to throw up a large amount of skeletons. Dagon starts to remember his friends but becomes angry when he remembers Hanami, and says that he will kill them for what they did to Hanami. Dagon then shed its skin and becomes a fully manifested cursed spirit. Dagon releases a large amount of water but the three manage to withstand the attack. Naobito starts to ramble on about frame rates in animation sequences, which Dagon ignores and comments about how he and his allies have names when Naobito refers to Dagon as "cursed spirit".

Dagon is then attacked by all three, and Dagon manages to defend itself by creating a water barrier. The three start to rush Dagon down with speed, which forces Dagon to retreat. Naobito manages to overwhelm Dagon, and Dagon notices that he can't use his technique because of Naobito's attacks. Dagon then manages to trap all three within its Domain Expansion. Dagon tests the three with his sure-hit technique and figures out which to take out first. Dagon uses it's Death Swarm attack to take out Nanami first and block Naobito's view. While Naobito's view is blocked, Dagon delivers a blow that sends Naobito flying and then swarms him with Shikigami. Dagon attacks Maki with a kick, while also proclaiming that she is the weakest. Maki returns and comments about how Dagon should have killed her with one attack, which Dagon decides to attack her like he did with the other two. Dagon is then shocked when Megumi Fushiguro breaks into his territory and delivers Maki the special grade cursed tool: Playful Cloud.

Dagon tries to attack Megumi, but Maki wounds Dagon with Playful Cloud. Dagon tries to use his domain's technique but notices that Megumi is blocking him from using his domain's technique. Dagon tries to attack Megumi, but Nanami, having survived the Death Swarm, comes to protect Megumi. Maki and Naobito then attack Dagon, and Dagon protects himself by using shikigami. When Nanami tells Maki and Naobito to "assemble", Dagon figures out their plan and chases after them. When Toji Fushiguro enters the Domain, Dagon thinks that that was their plan all along. As Toji prepares to fight Dagon, Dagon thinks about how Toji doesn't have cursed energy and attacks with a weak shikigami. Toji easily takes care of the shikigami and attacks Dagon, causing Dagon to wonder about the power that Toji has. Dagon attacks with more shikigami but again, Toji easily dispatches them. Dagon then sends out his strongest shikigami but Toji easily destroys them and continues to attack Dagon. Toji then rubs Playful Cloud together, causing it to sharpen at its ends.

Dagon thinks about how he is about to lose to a human with no cursed energy, but notices that Megumi's power is getting weaker and that he just has to buy time. Dagon tries to escape, but Naobito blocks his path and Toji takes this chance to stab Dagon. Dagon says that it's not over yet, but Toji continues to stab Dagon until Dagon is exorcised. Dagon is then mourned by Jogo, who burns Dagon's body.

Later when Jogo is killed by Sukuna, Dagon meets with Jogo along with Hanami in the afterlife.