Unlike Kamen Rider W’s novel, Kamen Rider OOO’s novel wasn’t written by its main writer. Instead, it was Nobuhiro Mori. Nobuhiro did however write 6 episodes for OOO, 21-22 (Grasshopper Yummy) and 33-36 (Owl and Unicorn Yummy).

Ankh’s section is set about 800 years ago. Leading all the way up to the sealing of the Greeeds and his encounter with Eiji, revealing that it was more than a coincidence that the two of them met. While it’s mainly about Ankh, the other Greeeds and the first OOO is also featured in this part.
When Ankh was first created, he resided within his 10 Core Medals not as the Greeed known as Ankh, but as the King of Birds. At that point Ankh felt free and was able to see the beauty in this world, he loved the vast blue sky more than anything. But as the 10th Core Medal was taken away, Ankh spawned from the Core Medals with his sense smell, vision and taste becoming distorted. He was unable to see the world in the same way he previously did and left with a feeling of being incomplete. He and the other Greeeds became the embodiment of greed. The King witnesses the birth of the Greeeds and says “Happy Birthday!” as he takes their Core Medals.

What sets Ankh apart and leads him to his betrayal to the other Greeeds begins when he meets a blind girl. This girl dreams of being able to a beautiful scenery accompanied with bluebirds. Ankh seems to be able to connect to the blind girl. Eventually become friends through their mutual desire to see the world in a beautiful perspective, even though Ankh hates humans. Ankh tells the girl that he’s actually a bird. The girl believes him and asks “Mr. Bird, what color are you?” Ankh responds with “I’m red…” leaving her rather disappointed as he’s not blue. Eventually Ankh tells her that he can help her see, and creates the Condor Yummy through her desire to see. The Condor Yummy attacks random people gouges their eyes out and gives them to girl. She opens her eyes and sees corpses with their eyes gouged out, seeing that she loses her mind and goes insane. She no longer has the desire to see again, and the Condor Yummy disintegrates into Cell Medals. Shortly after she dies and asks Ankh to once again become the King of Birds and protect the weak. Ankh feels bad for not being able to save her, in a similar way to Eiji and the girl he couldn’t save during the war.

Ankh joins up with the other Greeeds and agrees to take down the King together, in order to retrieve their Core Medals. The King is insanely strong and controls a large portion of Europe. He uses the combos very efficiently, with Gatakiriba he clones himself and destroys neighboring countries and their armies. He uses Tajador’s flight as his advantage and burns down villages that try and oppose him. With Ratoratah’s speed, he infiltrates enemy camp and strikes quickly. He uses Sagohzo and Shauta to cause earthquakes and tsunamis to take down the Spanish Armada. The Greeeds manages to get their Core Medals back too, but even when they are in their full form they can’t take on the King. In order to defeat him, they resort to using Yummies created from the King’s greed. Uva, Kazari and Mezool creates the Cockroach, Lion and Whale Yummies, they are almost as strong as a full form Greeed because of the King’s strong greed. But none of this is enough as Ankh reveals that he was working with the King all along, but the King betrays Ankh and leads up to all of them being sealed. Right before Ankh is sealed, he imagines and sees the blind girl, flying together and looking down on the beautiful world.

Birth’s part is completely different from Ankh’s. This one seems more like a net movie. It’s told entirely through the Birth Driver’s view. Despite being sentient, the belt isn’t capable of speaking human language. At one point the belt says “Sometimes I just want to scream, but then I realize I can’t.” But it is still able to communicate with other items, such as the Proto Birth Driver and other Candroids. The belt recollects his memories with Date and Goto, he goes on to praise Date by saying how strong he is, how masculine he is and how much fun they had together. Goto on the other was too unreliable and weak in the beginning, Birth Driver eventually came to accept Goto. The Prototype Birth Drive that was destroyed in Mega Max makes a brief appearance and says “A transformation belt that can’t transform is just a regular belt. Actually, it’s even worse. A regular belt is at least used as to keep someone’s pants up! I can’t even do that. I’m just a heavy object around the waist!”
Doctor Maki also makes a minor appearance by creating a Yummy from the Birth Driver. The Yummy is called Kamen Rider Desu and looks similar to Kamen Rider Birth,  but he’s not really a Kamen Rider. The Candroids, Mr. Gori and Mr. Tiger as the Birth Driver refers them as, destroy the Yummy.
At the very end, it’s revealed that the entire Birth chapter is a short story written by Akira Date out of boredom.

Finally, the last part of the novel is Eiji’s part. It serves as an epilogue for the TV series and as a prequel with some flashbacks of Eiji’s past.
This part tells the story of a girl called Alfreed and her brother Cain. Alfreed belongs to a certain tribe, located in a desert and the country is in civil war, fighting over the few resources they have. The country is heavily hinted to be a middle-eastern country. She was supposed to get married, but her fiancé died because of the war. Eiji, who traveled in order to learn more about the Arabic word “maktab” ends up meeting Alfreed. He follows her to her village and gets to know the people and their culture. As it turns out, Cain became an assassin for an enemy tribe in order to survive. Alfreed is eventually killed in the war, Eiji is saddened over this and to let this happen again.

It then flashes forward to sometime after Mega Max, judging by the amount of Core Medals he has. With no more Greeeds and Yummies, Eiji returns to that country and decides to help and put an end to the war. He does so by using the OOO Driver, in a similar way to what the King did. Starting with Tatoba as a diversion, he quickly uses Gatakiriba and destroys the soldiers’ guns, Ratoratah to destroy tanks and Sagohzo to stop rocket launchers. He uses Tajador to take down the airforces while safely rescuing the pilots. In the dried out deserts, Eiji uses Shauta in order to create rain. The enemy tribe gets scared and the war slowly stops.
As the novel ends, Eiji walks through the desert while continuing his journey to find a way to revive Ankh, as Ankh’s spirits slowly floats next to him and connects to the end of Kamen Rider OOO the TV series. This would basically mean that Mega Max is set during the final episode of Kamen Rider OOO, somewhere between the defeat of Maki and the epilogue in the TV series.