The intensive meditation retreat known as Rōhatsu sesshin 臘八摂心, held every year in Japanese Zen monasteries from the morning of December 1st to the dawn of December 8th, appears to have originated under the influence of the Ōbaku 黄檗 Zen sect, which was transmitted from Ming 明 China to Japan in the 17th century. Ming-dynasty Chan had a form of meditation training known as daqi 打七, a retreat that is recorded as having occurred in December. This is thought to have been the source of the Rōhatsu sesshin retreat instituted in Japanese Zen monasteries. Evidence for this is found in the Ōbaku sannnai shingi 黄檗山内清規 (Detailed regulations of Mount Ōbaku), which describes the custom of eating mixed rice gruel 五味粥 on the morning of December 8th, a custom also observed at the end of Rōhatsu sesshin in Japan.
