Bankei was born in the early 17th century in Harima Province to Suga Dosetsu. His mother's information is little known only. It is recorded that the mother had the last name of Noguchi. Bankei had four brothers and four sisters. In his childhood period, he was better known as Muchi and was a rebellious and mischievous child but at the same time, he was intelligent.
He enrolled the school in the same year when his father died. In his early days, he was taught many Confucian texts. While learning the philosophy of Confucian, it confused him greatly and entered into the heated discussion with his teacher. The answers given by his teachers were not satisfactory to him. Therefore, this confusions gave birth to various doubts and questions. To get the satisfactory answers, he used to question others- Confucian and Buddhist scholars and also used to attend various religious gatherings. But the efforts used to be in vain. He was so distressed to get his answers that the school was no longer a priority for him.
Hence, he was expelled from the school and also kicked out of his family home. With the help of his family friend, Yukan Nakahori, he stayed in a small hut and placed a slat of wood outside of his hut mentioning Practice Hermitage.
Training under Buddhist module
At the very young age, Bankei began to practice Shin Buddhism. It is recorded that he trained at a Shingon temple, at the age of 15, where he gained learned about the sutra. But he was not satisfied with the approach and ultimately left the temple. At the age of 16, he walked to Ako to see a Rinzai Zen priest, Umpo Zenjo at Zuio-Ji temple. He then requested to teach him the meaning of bright virtue. Umpo in reply suggested him to the practice of zazen to learn the meanings though it might be hard to get the answers. Bankei was impressed and then ordained as a monk at Zuio-Ji temple under Umpo. He then received his Buddhist name Yotaku which means Long Polishing of the Mind Gem.
Bankei later left Zuio-Ji Temple and then traveled through Kyoto, Osaka, and Kyushu in search for an answer to his questions. With no progress, he again returned to the temple and visited Umpo. Umpo then informs him that the answer could only be found through within not through an intermediary. Listening to the words of Umpo, he left the temple shortly and then built a small hut nearby and then lived as a hermit. He then practiced zazen for hours. He gave up bodily comfort and had no other goal except his one and only understanding of complete things. He lived and practiced this way for many years but eventually, he got tuberculosis due to the neglect of the bodily environment.
When he was experiencing near death, Bankei realized the Unborn. He observed and feel the activity, mindfully during his last moment and all his queries were resolved in this Unborn. With his doubt and questions ceased, he physical condition turned better once again. He again traveled and returned to Umpo to share his experience. After the meeting, Umpo confirmed his enlightenment. He was sent to Gudo Toshoku, Rinzai master with the purpose to evidence the Bankei's understanding.
When Bankei visited Gudo, he found that Gudo was attending to another temple. So Bankei visited the other temples. While communicating with the abbot, Bankei found that they hadn't proper understanding themselves to confirm his understanding. He then returned to Umpo. Later in the mid 17th century, Bankei heard that Ch'an master, Dosha Chogen, arrived in their locality. Umpo advised Bankei to visit the Chan master to confirm the enlightenment.
When Dosha Chogen met Bankei, he confirmed the understanding but also informed that Bankei's understanding was incomplete. Initially, Bankei refuse the words of Dosha but when he observes Dosha's way of practice, he realized that Dosha was true. So Bankei stayed and practiced under Dosha.
While meditating, Bankei experienced the final awakening. Dosha confirmed this the next day. He stated that Bankei had finally settled the matters. Bankei was approached with the senior position in the monastery but he refused and instead worked in the kitchen. He later returned to Harima and then left for Yoshino in the Nara Prefecture to live again as a hermit. He authored some Buddhist chants while living in the mountains of Yoshino in a silent retreat.