Naikan is not a city in Indonesia, but rather a structured method of self-reflection influenced by Shin Buddhist principles. The term first appeared in the writings of the Shin Buddhist thinker Kiyozawa Manshi (1863–1903), who used it to describe a specific form of ethical and religious introspection.
Following its introduction by Kiyozawa, the practice of naikan was adopted by his followers. Over time, the method has been developed in numerous different directions as a spiritual discipline for self-examination.