Using ubiquitous devices such as multifunctional cellular phones and PDAs, we can build a large-scale navigation system for evacuation in the metropolis. Although current navigation systems simply broadcast the same instructions over a large area, the required function is to provide individualized instructions to each user. Our approach is to build a navigation system based on multiagent system which assigns one guide agent to each user. In the system, a guide agent can provide personalized navigation instructions depending on its owner's surrounding circumstances. We implemented Mega-Navigation system using massively multiagent platform, called Caribbean/Q. Our Mega-Navigation system, which is currently able to work for evacuation in the city of Kyoto, can catch evacuees' position and offer instructions through GPS-capable cellular phone. Categories and Subject Descriptors I.2.11 [Artificial Intelligence]: Distributed Artificial Intelligence--Intelligent agents, Multiagent ...