The military subject which Ocho-Kokka faced was Kyoto-hoki (凶党蜂起)--an armed struggle against Kokuga (国衙) power by various power which was in a district--and to oppress such a struggle Orho-Kakka formed the peculiar army Kokuga-Gunsei through Kokuga.
In this paper, first, the author regards Kokuga-Gunsei as the army to realize "arrest" in a series of criminal procedures for "Juhan (重犯)". Secondaly, the author solves concretely how the army was formed and what enabled the formation. Finally, the author considers several steps of Kokuga-Gunsei which succeeded to the army of Ritsuryo-Kokka (律令国家) and developed into that of Kamakura-bakufu (鎌倉幕府), and gives his view on the formation of the medieval army and the relationship between lord and vassal.