When Asa’s mother goes into labor yet again, Asa runs off to find a doctor. But no one bats an eye when she doesn’t return—not even as a storm approaches Nagoya. Forgotten yet again, Asa runs into a burglar and tries to stop him on her own, a decision that leads to an unlikely alliance.
Asa and Kasuga see the tail of a giant creature rise from the water. In a jungle, explorers discover massive claw marks in a tree trunk. And years later in 1964, a mysterious military man appears asking all the wrong questions.
With the Olympics around the corner, the Japan Defense Forces have their hands full. So Jissoji enlists Asa and Kasuga’s help to find, identify and deal with the mysterious creature that decimated Asa’s hometown.
Asa reluctantly agrees to accompany Yone to an audition at an entertainment agency. However, before they can leave, Mr. Jissoji shows up with news—the mysterious creature has been spotted! With Kasuga nowhere to be found, Asa prepares to take flight to identify the creature. But before she can, Nakaido runs in claiming to have found its weakness, earning himself a seat in Asa’s plane as they take to the skies.
Asa and Nakaido fly out to take a closer look at the mysterious creature that has appeared off the coast of Japan. As the creature threatens them with its sharp teeth and spiky tail, Nakaido works to decipher his mentor’s notes and find its weakness. But their attempts to take down the beast are in vain when it makes its way for land!
After driving away “that thing” that appeared off the coast of Japan, Asa returns home to questions and speculation from her siblings and friends and a warning from Kinuyo—no more dangerous flying! Meanwhile, Jissoji goes to the hospital to visit the prime minister, who not only knows about Asa—he believes the fate of Japan rests on her shoulders! At the prime minster’s insistence, Asa is told to be ready to spring into action at any time.
The mysterious creature appears in Tokyo Bay and takes a chunk out of a self-defense forces vessel. Asa is called into action, but she has trouble reaching the airfield due to the Olympic crowds. Meanwhile, Shota arrives at the same beach as the creature. Asa and Kasuga finally get up in the air and do a flyby, but the creature damages their plane, causing them to lose altitude. Will Asa be able to regain control?
Using a stage name, Yone auditions for several record companies before seemingly getting her big break from Shibahama Music Factory, but she later learns fame can come with a cost. Meanwhile, Shota becomes obsessed with spotting the sea monster so he can use the drug to fight it again. Later, Asa and Nakaido discover an interesting clue in Professor Yodogawa’s belongings that brings them one step closer to uncovering the mystery behind the monster.
After stealing Yone’s film, Asa comes face-to-face with River Etheridge, the man who wrote the song that she’s been singing since childhood. Meanwhile, Jissoji’s operatives aren’t pleased with Asa’s disappearance. Kasuga heads to Shibuya to search for her, but “that thing” could strike at any moment!