Ryokan Taigu, also known as Taigu Ryokan, was a Japanese Zen poet and hermit who lived during the late Edo period. He was born in 1758 in the village of Izumozaki, located in present-day Niigata Prefecture, Japan. Ryokan's given name was Eizō, and he was the second son of a village headman.

As a child, Ryokan showed a deep interest in Buddhism and often spent time at the local temple, where he learned to read and write. However, his formal education was cut short when he was only nine years old, as his family could not afford to send him to a Buddhist monastery for further studies.

Despite this setback, Ryokan's passion for Buddhism continued to grow, and at the age of 18, he left his family and village to become a monk. He first studied at a nearby temple, but soon after, he moved to Eihei-ji, one of the two main temples of the Sōtō school of Zen Buddhism.

During his time at Eihei-ji, Ryokan immersed himself in the study and practice of Zen Buddhism. He also became a disciple of the famous Zen master, Gesshū Sōko, who had a significant influence on Ryokan's spiritual development.

However, Ryokan's monastic life was short-lived. After only five years, he left Eihei-ji and returned to his village, where he lived as a wandering monk for the next few years. During this time, he traveled across Japan, visiting various temples and studying under different masters.

But in 1790, at the age of 32, Ryokan decided to leave the monastic life behind and become a hermit. He moved to a small thatched hut on Mount Kugami, where he lived in seclusion for the rest of his life.

There are various theories as to why Ryokan chose to become a hermit. Some say it was due to his disillusionment with the corruption and politics within the monastic community. Others believe it was a result of his desire for a simpler and more solitary life, free from worldly distractions.

Regardless of the reason, Ryokan's decision to become a hermit was a significant turning point in his life. It allowed him to focus on his spiritual practice and writing, which ultimately led to his fame as a Zen poet and hermit.

In conclusion, Ryokan Taigu became a hermit after spending several years as a wandering monk and studying under various Zen masters. His desire for a simpler and more solitary life, combined with his passion for Zen Buddhism, led him to leave the monastic community and live in seclusion on Mount Kugami.