Sana introduces the main characters, and Mariko.
It's a virtual laser game. Sana's team is losing. Sana fights back with a whirlwind shooting style that zaps everyone out except for Zenjiro. But Sana has Hiroshi dive on top of Zenjiro so her team wins. After the game, Zenjiro hints whether Sana has a boyfriend. Sana thinks and tells the camera about going to the amusement park with her sister, well, a kid that she treated like a little sister. She calls out Mariko's name on television, inviting her to come have fun with her sometime. Mariko sees Sana on Child's Toy and she tells mom. Mariko's mom, Keiko, wonders if she was serious since they weren't on speaking terms since the meet.
Sana is on location at the tennis courts. As Sana leaves the bus, she is greeted by the fans.
Mariko and Keiko are outside their laundry service store. Mariko is doing chalk drawings of Sana when Keiko gets called in by Mariko's dad. She tells Mariko to stay, but moments later, Mariko hears some girl talk about Sana being nearby, and she follows them.
Sana plays tennis with the Child's Toy gang. A group of fans are watching, but Mariko can't see anything. She boards Sana's bus. Zenjiro is exhausted from playing tennis. His agent, Sanekichi, tells him his lunch is on the bus. As he boards, he sees Mariko eating his lunch sandwich and scolds her. Mariko cries, so Zenjiro quickly rushes to get her a drink and amuse her a little. Then Zenjiro has to leave for some more tennis retakes.
Keiko and her husband look for Mariko outside the store and the nearby streets, but don't see anyone. The bus has already left and Sana's on board entertaining the crew.
Mariko wakes up but no one is on the bus. Then she sees Sana and the group entering the studio. Meanwhile, Keiko calls Misako telling her about her missing daughter and that Sana might be connected. Misako asks Shimura to "fetch the item". Mariko wanders the studio looking for Sana and finds a dressing room with a white suit. Rei, who responds that he will get his old network (the homeless guys) to help look for him. Sana hears about Mariko going missing and sends a burutcha message for Akito, who is playing video games with Tsuyoshi. Akito gets the message but it's in some weird code, so he has to pull out a thick decoding book written by Sana.
Zenjiro is frustrated with work, and decides to head home. When he reaches his dressing room he sees that his white suit had been colored all over with markers and he spots Mariko. He rushes to Sanekichi telling them a kid is in his room, but when he comes back, Mariko had left the room. Meanwhile, Misako and Shimura control "the item", which is a floating balloon with a camera.
Sana is the guest of a cooking show with two other women. She demonstrates how to make green tea sausage rice, but her segment only last less than a minute, and then she leaves early. Sana sees Mariko's parents, who apologize to each other about losing Mariko. Rei arrives and tells them they spotted her at the TV station.
Zenjiro wears his magic-markered white suit as he leaves the studio. He has to drive a rental car but they give him a pickup truck. As he boards the truck, he sees Mariko and tells her to go away since Sana isn't there, but she doesn't.
Sana interrupts several other TV broadcasts looking for Mariko. But Mariko is with Zenjiro on the road. She tells Zenjiro she needs to go potty, so they stop by a convenience store, where one of the homeless guys spots them.
Sana and Mariko's parents search the studio some more. Mariko's dad asks around, showing his obsession. Keiko tells Sana how dedicated he is to Mariko. Rei arrives and tells them they spotted Mariko!
Zenjiro arrives at his house but then soon afterwards the police storm the place and find Mariko. Her dad delivers a big punch to poor Zenjiro's face! Sana explains that Mariko's dad apologized to Zenjiro afterwards.
Tsuyoshi and Akito are at Sana's house with Sana, Misako, and Mariko. They couldn't make any sense of Sana's decoded message. Sana decides to celebrate the occasion with a song, and she waltzes with Mariko.
In the final scene, a scary middle-aged woman (Ms. Andoh) looks at Sana's test paper and her makeup starts to crack.