Wikipedia
The was an influential medieval Buddhist text composed in 985 by the Japanese Buddhist monk Genshin. Three volumes in length and in kanbun prose, the text expounds on Pure Land Buddhist thought, with emphasis on methods to attain rebirth in the Pure Land of Amida Buddha, drawing upon earlier Buddhist texts such as the Contemplation Sutra. Genshin emphasized visual meditation practices, where later Pure Land sects favored verbal acts such as the nembutsu. The text is also well known for its graphic descriptions of the Hell realms, and sufferings one might endure for harmful acts committed in this life. Its influence can be seen in Japanese Buddhist paintings and other, later, texts. The founder of Jōdo Shinshū Buddhism, Shinran, wrote an influential commentary on the Ōjōyōshū titled, "Notes on Essentials of Rebirth", while Hōnen first encountered Pure Land teachings after studying Genshin's writings.
In 986, a copy was sent to China, where the monks where impressed enough to call Genshin the "Little Shakyamuni".