At events and sightseeing spots, congestion can be a factor that lowers customer satisfaction, so there is need for methods that mitigate congestion. Currently, there are methods for mitigating congestion such as changing the layout of an event and restricting customer behavior. However, there are problems in that it is difficult to reduce congestion at events in which the layout cannot be changed, and there is a risk the satisfaction level will be reduced due to restricting customer behavior. Therefore, we propose a method aimed at reducing congestion by allowing users to voluntarily select a detour to avoid congestion by providing users with not only obvious information but latent information with a walk-rally application. In demonstration experiments at real events and sightseeing spots, we confirmed that the proposed method is effective at reducing congestion and clarified how to use latent information effectively for mitigating congestion.