Buddhism Zen Buddhism is divided into two main schools: Rinzai (臨済宗) and Sōtō (曹洞宗), the former greatly favouring the use in meditation on the koan (公案, a meditative riddle or puzzle) as a device for spiritual break-through, and the latter (while certainly employing koans) focusing more on "shikantaza" or "just sitting". Zen Buddhism is primarily found in Japan, with some presence in South Korea and Vietnam. The scholars of Japanese Soto Zen tradition in recent times have critiqued the mainstream Japanese Buddhism for "dhatu-vada", that is assuming things have substantiality, a view they assert to be non-Buddhist and "out of tune
Zen at War types of social discrimination found in Sõtõ rituals and temple practices" find their origin in "the medieval institutional regulations imposed by the Tokugawa regime, not in the religious attitudes, religious practices, or religious mission of Sõtõ Zen itself". The Soto-school has installed a Human Rights Division, to terminate the regulations which contribute to discriminatory practices. "Zen at war" has contributed to discussions on the meaning of "enlightenment", and the role of Zen-teachers in the emerging western Zen-Buddhism. Bodhin Kholhede, dharma heir of Philip Kapleau, says: Stuart Lachs has written several essays on this issue, connected to teacher-scandals in western sanghas.