Hakuin Ekaku, also known as Hakuin Zenji, is a highly revered figure in the history of Zen Buddhism. He is known for his role as the reviver of Rinzai Zen, one of the main schools of Zen Buddhism in Japan.

Hakuin was born in 1686 in a small village in Japan. He was raised in a family of Zen priests and from a young age, showed a deep interest in Buddhism. He began his formal training in Zen at the age of fifteen and spent the next several years studying under various Zen masters.

Hakuin is known for his intense and rigorous approach to Zen practice. He emphasized the importance of zazen, or seated meditation, as the key to attaining enlightenment. He believed that through dedicated and disciplined meditation, one could transcend the limitations of the ego and experience the true nature of reality.

One of Hakuin's most significant contributions to Rinzai Zen was his development of the koan practice. Koans are paradoxical questions or statements that are used as a tool for meditation and to challenge the student's understanding of reality. Hakuin believed that working with koans could help students break through their conceptual thinking and reach a state of pure awareness.

Hakuin was also known for his skill in teaching and his ability to inspire his students. He was a charismatic and dynamic teacher, known for his sharp wit and unconventional methods. He often used shock tactics and unconventional methods to push his students out of their comfort zones and help them break through their limited thinking.

In addition to his teachings, Hakuin is also known for his extensive writings, which include commentaries on Zen texts, letters, and poems. His writings have been highly influential in shaping the understanding and practice of Zen Buddhism.

Today, Hakuin is revered as one of the most influential Zen masters in Japanese history. His teachings and methods continue to be studied and practiced by Zen students around the world. His legacy as the reviver of Rinzai Zen has had a lasting impact on the development of Zen Buddhism and continues to inspire practitioners to this day.