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)