Using the Masked Rider System developed by the secret organization of ZECT, Tendo Soji fights the Worm, extraterrestrial life forms that murder and mimic human beings.
Seven years ago, a meteor slammed into the city of Shibuya and destroyed it, carrying with it the Worms, alien lifeforms that blend into the human population by copying people’s forms. The paramilitary corporation ZECT fights the Worms, developing the Masked Rider System as their anti-Worm weapon. When the paths of ZECT member Kagami Arata and the mysterious Tendou Souji cross, the day Souji has waited for finally arrives, as he is the man who walks the path of heaven…
Arata struggles with the Kabuto Zecter having chosen Souji over himself, especially in the face of Kabuto’s defeat against the Worms’ Clock Up ability. After enjoying a meal at a small French cafe, Souji and Arata rush into another battle with the Worms where Souji reveals that he knows more about the Masked Rider System than he first let on, gripping the Kabuto Zecter…
A woman named Yuki is attacked by the Lanpyris Worm and impersonated, but she survives, leaving two Yukis running around, but one is swiftly captured and imprisoned. Tensions increase between Souji & Arata, who is quickly falling out of favor with ZECT, as Souji sets the stage for the two Yukis to meet face to face again, kicking off a fight at an amusement park...
Arata must face the difficult truth about who his younger brother really is. Souji confronts Arata, telling him that he will defeat the Worms, no matter who they are. In the end, Arata is left with the toughest choice of his life, as the rain begins to pour…
Ending up at Souji and Juka’s home, Hiyori and Juka bond over their shared history of being present for the Shibuya meteor strike. Later, Souji offers to join Hiyori at the Tokyo Tower, but when ZECT sets their sights on Kabuto, will he be forced to break his promise?
Having been taken in by ZECT, Souji makes several demands, including speaking to Juka and asking Hiyori to make her breakfast. Arata begins to worry about Souji, but when he arrives at ZECT, Souji has already begun his escape. In the process, he learns that two of the ZECT members are Worms, and Arata tries to warn Misaki, but it may be too late...
Arriving from ZECT HQ, Kamen Rider TheBee joins the fight as Arata warns Souji to stay out of ZECT’s affairs now that they have a Rider following their orders. However, he ends up butting heads with TheBee’s user, Yaguruma Sou, ending up in a battle of tofu dishes with Hiyori as the judge. But will their clash in the kitchen spill over to the battlefield?
Souji turns out to have been correct about the other Worm escaping, so Shadow, now with Arata as part of the team, sets up at another wedding, locking it down. However, Souji manages to breach their defenses and takes on the Worm, but an angry Yaguruma won’t let this go and the two Riders face off…
As Kabuto and TheBee fight, Arata tries to stop them, giving TheBee an opportunity to gain the upper hand and destroy Kabuto’s belt. As Souji recovers from the battle, Arata struggles with his position as Hiyori once again remembers a memory of her past…
To defend the team from the Worms after Yaguruma loses his transformation, Arata obtains TheBee Zecter and transforms, finding himself as the new captain of Shadow. But can he fulfill the orders given to him from HQ?
Kagami is ready to cancel his group date until it's suggested that Tendou join him; a man with a young girl is seen walking around with a large makeup kit.
Kageyama joins Misaki's team after the Shadow team has been dissolved; someone within ZECT is leaking information and former Shadow team members are getting killed.
Tendou joins the Shadow unit as the captain, much to the chagrin of Kageyama; everyone is confused when three of the same doctor appear at the same place and none of them are attacked by a Worm.
Tsurugi heads out for groceries and causes an accident involving Tendou's little sister; the Phantom Shadow have their eye on one of Tsurugi's heirlooms.
Tendou is given a knife by a dying man who wants to see it given to its proper owner; Junka visits a restaurant that has had all of its customer's stolen by a place across the street with a new chef.
After being defeated by Tendou, Daisuke finds Rena who is now not aware that she is a Worm; Tsurugi asks Kagami to help him ask out Misaki; Tendou laments about not being able to find a way back to Hiyori.
Tendou and Kagami wonder if Hiyori was telling the truth about not wanting to return; ZECT is having a hard time trying to keep an army of Worms out of Area Z.
