Before he can gouge out her eyes, everyone's attention is caught by a loud noise from the ridge above. The source: the man on the bike, his helmet now transformed into a grasshopper-like mask. The spider mask recognizes him with delight: "Batta Aug", who immediately jumps down to the forest and starts attacking the spider's minions, allowing the woman and the spider-masked man to leave the scene unaccosted. Only when the bloodbath ends does Batta Aug leap away.
Cue title card: Shin Kamen Rider
In an abandoned house, brought there by the woman, Batta Aug is in shock, hearing wind from inside of his body and wondering how he could kill people so easily. His horror grows when he gets a look at his body, now mutated to give him great strength. It's not until a third, older man enters the house that Batta Aug—and the audience—start to get some answers.
"Batta Aug" is Takeshi Hongo, a brilliant though socially-withdrawn college graduate and motorcycle enthusiast. The older man is Professor Hiroshi Midorikawa, Hongo's college professor and the one who had him "upgraded" into a half-grasshopper mutant. The woman is Ruriko Midorikawa, the professor's daughter, who had freed Takeshi from the Organization shortly after they had augmented him, leading to their pursuit.
Professor Midorikawa explains that Takeshi is now an Augment, a human being with superhuman abilities thanks to possessing a large amount of prana, an omnipresent life force that all living things generate. With the Organization's other Augments only using their prana-granted powers for their own gratification, Midorikawa had decided that the future of prana could only be entrusted to Takeshi, who is horrified by his new power, but isn't able to argue. Hiroshi declares that they need to destroy the Organization and thus require Takeshi and his new abilities to do so; and Ruriko fastens a red scarf, a motorcycle rider's garment, around Takeshi's neck to distinguish him.
Suddenly, the spider-masked man—Kumo Aug—knocks out Ruriko, grabs the professor, and webs Takeshi to the wall. Takeshi can only watch helplessly as Kumo Aug strangles Midorikawa, who gasps out to Takeshi to take care of Ruriko before his dead body dissolves into nothing. Kumo Aug then leaves the house, planting a bomb and taking Ruriko away. The blast completely pulverizes the house—but Takeshi manages to leap away unscathed. He immediately gets on the bike from earlier, his personalized motorcycle Cyclone, and moves to intercept Kumo Aug, transforming himself into his Batta Aug form along the way.
At Uoguchi Dam, Kumo Aug is confronted by Takeshi, who rejects his "Batta Aug" label and declares his identity as "Kamen Rider". Dismissive, Kumo Aug sics more of his minions on Kamen Rider before fighting him one-on-one. Unable to understand why Kamen Rider doesn't find any happiness in killing humans as he does, Kumo Aug restrains the renegade with his multiple arms. Kamen Rider turns the tables by jumping into the air with Kumo Aug, spinning fast enough to dislodge the assassin and striking him with a prana-powered flying kick. Dead, Kumo Aug's body dissolves - a fail-safe that destroys any evidence leading back to the Organization.
Kamen Rider recovers Ruriko, who is alive and unharmed from the kidnapping, and not as unconscious as she appeared. After she disengages his transformation, Takeshi comments that what he did pains him, and can only bow his head in mourning for Kumo Aug and his minions. Ruriko dismisses Takeshi's apologies for failing to save her father, revealing that her relationship with Midorikawa was quite distant, and even shrugging off Takeshi's suggestion that his new body was made because of Midorikawa's love for his daughter. Ruriko offhandedly wonders if Takeshi's kindness was the biggest factor in Midorikawa choosing him to fight the Organization.
The two ride away from the Dam on the Cyclone, seemingly unaware of the metal humanoid in a purple suit observing them. That same metal humanoid reports the death of Kumo Aug to someone named "Ichiro-sama", who seems to have a connection with Ruriko, and has a second man ready to match the renegade Batta Aug...
