While waiting for Osamu, Yūma meets a girl called "Chika Amatori". They take some time to know each other, but Chika runs off when the Danger Alarm starts ringing, and it's up to Yūma to find out why.
The chapter begins with a young girl under a bridge. She checks her cell phone, saying she seems to have arrived too soon. She then hears a noise and turns around to see Yūma, who fell to the ground while riding a bicycle. She asks Yūma if he's alright, and he says he is, and that somehow he never gets hurt.
She then asks Yūma if he's training to ride his bicycle and he says that he's waiting for a friend, but in the time being, since he has nothing else to do, he's training to ride with a bicycle. She says she also has an appointment with someone. He asks her if she knows how to ride a bicycle, and she says she does, to which Yūma answers by saying she's "lucky", which makes her embarrassed.
Yūma then says that "this vehicle" (the bicycle) seems to be always falling, and that he thought there was some kind of trick to make him go straight forward, and that he was surprised that there wasn't. He says that if he cannot unveil the secrets of the bicycle, then continuing to go forward will be a mystery to him. He then asks her if the Japanese have some kind of special training to ride bicycles, and she asks herself if he's a foreigner.
She then answers a Phone call, while Yūma falls in the bicycle again, prompting her to go help him again. She starts pushing him in the bicycle, and he finally feels like he's learning how to ride the bicycle, but he ends up falling into the water.
After getting out of the river, Yūma says his bicycle which he worked a lot to buy almost met its end in the river, and he and the girl finally introduce themselves to each other. The Danger Alarm then starts ringing and Chika says she has to go. Replica notices she knew there would be a Neighbor Attack even before the Alarm ringed, and Yūma decides to follow her.
In the Danger Zone, Chika finds a Vander but hides before it could see her. Meanwhile, Osamu arrives at the meeting point, where he sees Yūma's bicycle was left behind. He then asks himself where Yūma has gone. Back in the Danger Zone, Chika's cell phone start ringing and the Vander spots her.
Yūma arrives just in time, catching her before the Vander does. Yūma asks Replica if he can use his trigger, but Replica says that Border has begun a battle in the area. He then says Osamu is near, and Yūma decides to leave it for him, which surprises Chika. Osamu then arrives, and Replica's clone tells him about Vander, and says Yūma is near. Osamu activates his Trigger Mode, revealing his new B-Class uniform. He then activates the Thruster and quickly defeats the Vander.
Yūma says that he was impressive, and that's what is expected from a B-Class, but Osamu instead calls Chika's name, which confuses Yūma. Osamu asks her why did she enter the Danger Zone, and she said she thought it would be dangerous if the Neighbor came to the town. Yūma, confused by the fact they knew each other, asked if they did. Osamu said yes, and said that he called them both because he wanted Yūma to meet her. Osamu then tells Yūma and Replica that he needs information from them, saying Chika attracts Neighbors.