Gengo is a manga artist who has been tasked with creating a kaiju based on what children dislike. His editor tells him that he does not think his latest idea has potential, and so Gengo is sent on his way. Later on, his girlfriend suggests that he get a job at World Children's Land. He goes to Children's Land and learns some things about the under-construction park, such as its focus on Monsters. he is shown a model of the park, and suggests to his guide Kubota, that the park have some monsters of its own, so he pitches his ideas for Shukra (The monster of homework) and Mamagan (The Monster of strict mothers) The next day, Gengo visits the World Children's Land Planning Committee in downtown Tokyo but on the way in he runs in to a young woman who drops a tape recording and flees Gengo picks up the tape and stows it in his bag. Gengo then enters the building, and is introduced to the head planner for World Children's Land Fumio Sudo. He gives his ideas to Sudo, and heads home, only to be "mugged" by the girl he got the tape from earlier (Mackiko Shima) and her associate (Shosaku Takasugi). They explain to Gengo, that they have stolen the tape because the girl's brother told her that something diabolical is happening at Children's Land. He begins to discover where at Children's Land Machiko's brother is being held. He and Takasugi go to city hall to find records on the Children's Land chairmen, and find what is listed as their childhood home, only to realize that Fumio Sudo has been dead for a year. When they return to their base of operations, they are stormed by Kubota, who takes back the tape. They then decide to rescue Shima's brother from the tower and Gengo is sent into the tower to tell him. They successfully rescue him and the monsters destroy World Children's Land.