Sekai no Hikari: Shinran Shounin(1992)

Young Matsuwakamaru loses his father as an infant. To make matters worse, his beloved mother Kikkou passes away when he's 8 years old. While facing her death, Matsuwakamaru is puzzled at where people go when they die. If there is a cycle of heaven, hell, and rebirth, is there a way to escape this torturous circle, he wonders. With this great determination for the discovery of knowledge in mind, at only 9 years old, he joins a Buddhist monastery on Mt. Hiei, and changes his name to Shinran. This is the story of the man who would someday open the doors to the Joudo Shinshuu sect of Buddhism.

(Source: Anime News Network)