Tettsū Gikai received dharma transmission

Dharma transmission

Dharma transmission refers to "the manner in which the teaching, or Dharma, is passed from a Zen master to their disciple and heir...

 from Koun Ejō

Koun Ejo

Koun Ejō was initially a disciple of the short-lived Darumashū sect of Japanese Zen under Nōnin, but later studied and received dharma transmission under Dōgen and is considered his spiritual successor by the Sōtō school. His transmission is the final koan chronicled in the Denkoroku...

 and is considered his spiritual successor by the Sōtō

Soto

Sōtō Zen , or is, with Rinzai and Ōbaku, one of the three most populous sects of Zen in Japanese Buddhism.The Sōtō sect was first established as the Caodong sect during the Tang Dynasty in China by Dongshan Liangjie in the 9th century, which Dōgen Zenji then brought to Japan in the 13th century...

 school of Zen

Zen

Zen is a school of Mahāyāna Buddhism founded by the Buddhist monk Bodhidharma. The word Zen is from the Japanese pronunciation of the Chinese word Chán , which in turn is derived from the Sanskrit word dhyāna, which can be approximately translated as "meditation" or "meditative state."Zen...

. However, this was not clear at the time; many monks supported his rivals, Jakuen

Jakuen

Jìyuán , better known to Buddhist scholars by his Japanese name Jakuen, was a Chinese Zen monk and a disciple of Rujing. Most of his life is known to us only through medieval hagiography, legends, and sectarian works. It is generally agreed, though, that during his time at Tiāntóng Mountain he...

, Gien and Giin, and the sandai sōron

Sandai soron

The sandai sōron , or third-generation differentiation, was a dispute over the orthodoxy and succession of Sōtō Zen Buddhism. The major figures involved were Jakuen, Gikai, Gien, and Giin, all of whom claimed the right to serve as abbot of Eihei-ji...

was not resolved during his lifetime.

He was controversial with the other monks because he introduced innovative practices aimed at making Sōtō more popular with the Japanese laity, which some claimed Dōgen

Dogen

Dōgen Zenji was a Japanese Zen Buddhist teacher born in Kyōto, and the founder of the Sōtō school of Zen in Japan after travelling to China and training under the Chinese Caodong lineage there...

 would have frowned upon. However, he also had many followers, and eventually his innovations became the standard form of Sōtō Zen. His disciple Keizan

Keizan

-Biography:Keizan Jōkin 螢山紹瑾 , also known as Taiso Jōsai Daishi, was the second of the great founders of the Sōtō Zen sect in Japan. While Dōgen Zenji, as founder of Japanese Sōtō, is known as , Keizan is often referred to as Taiso , or Greatest Patriarch...

expanded on his plans for Sōtō and became the second most famous figure in the school's history.