Ojoden refers to a memoir of a person who reached the celestial realm (the Pure Land of Amitabha (Amida Buddha)) and was transformed to Buddha or to the collection of such memoirs, and "Nihon Ojo Gokuraku-ki" is considered the oldest ojoden in Japan.
往生伝とは、極楽往生をしたものの伝記またはその伝記を集めたもので、日本往生極楽記は日本で最古の往生伝とされる。