This paper attempts to rethink the ancient Emperor's Capital transition process from the viewpoint of territorial history. Emperor Tenmu, who planned first capital as Fujiwara-kyo in Asuka region, had a grand plan to put multiple cities in Japan. At that time the important cities were situated along east-west axis. However, since relocation of the capital from Fujiwara-kyo to Heijyo-kyo, the axis had turned towards north-south direction. The last ancient capital Heian-kyo was clearly organized utilizing north-south water systems in territorial sense.