Ushiro no Hyakutarou

Horror OVA based on the manga by Jirou Tsunoda. The title roughly means "Hyakutarou behind". A boy named Ichitarou Ushiro deals with various horrifying phenomena with the help of his guardian spirit Hyakutarou. 2 episodes: "Kokkuri Satsujin Jiken", "Yuutai Ridatsu". (Source: AniDB)