Obaku Zen is a unique blend of Zen Buddhism and Pure Land Buddhism, and its history can be traced back to 17th century Japan. It was founded by Chinese Zen master Ingen, also known as Yinyuan Longqi, who brought his teachings to Japan after being invited by the shogun Tokugawa Iemitsu.

Ingen was a disciple of the famous Chinese Zen master, Linji Yixuan, and had studied under him for over 30 years. He was well-versed in both the Linji and Caodong schools of Zen, and his teachings were greatly influenced by these traditions. However, upon his arrival in Japan, Ingen found that the Zen practices there were quite different from what he had learned in China. This led him to establish the Obaku school, which aimed to combine the best elements of both Zen and Pure Land Buddhism.

The name "Obaku" is derived from the Chinese characters "O" and "Baku," which mean "great" and "bodhi" respectively. This name reflects the school's goal of achieving great enlightenment through the practice of Zen. The Obaku school also incorporated elements of Pure Land Buddhism, particularly the recitation of the nembutsu (chanting the name of Amida Buddha) and the use of visual aids such as statues and paintings to aid in meditation.

Ingen's teachings were well-received by the Japanese people, and the Obaku school gained a large following. He established the first Obaku temple, Manpukuji, in Uji, and many other temples were built across Japan in the following years. The shogun Tokugawa Iemitsu became a patron of the Obaku school, and this helped to further its popularity and influence.

One of the key features of Obaku Zen is its emphasis on meditation and the use of koans (paradoxical riddles or statements) to aid in the practice. This is in line with the Zen tradition, which places great importance on direct experience and insight rather than relying on scriptures or teachings. However, the use of Pure Land elements, such as the chanting of the nembutsu, also sets Obaku Zen apart from other Zen schools.

Today, Obaku Zen continues to thrive in Japan and has also spread to other countries such as China, Korea, and the United States. It remains a significant school of Zen Buddhism, known for its unique blend of Zen and Pure Land elements and its emphasis on meditation and direct experience. The teachings of Ingen and the Obaku school continue to inspire and guide practitioners in their pursuit of enlightenment.