Recently, the need for scenarios is increasing due to the increasing number of large-scale games, and the development of an automatic plot generation framework is needed to reduce a scenario writer’s workload. In previous studies, the main focus was to output the complete scenario from scratch. However, there is a problem in that the story does not have a degree of freedom and loses diversity, which is needed to avoid the breakdown of a story. In this study, we aim to generate stories with a high degree of freedom without any breakdown. We regard a story as a hierarchical structure and use a structural theory method to gradually generate the scenario. We performed an evaluation experiment where we generated the plot, which is the first stage of scenario generation, automatically using the thirteen-phase theory, which is a type of scenario structure. The results of the evaluation demonstrate that it was possible to automatically generate something close to a plot created by a scenario writer.