Paper short abstract:

In the new kind of Shugendō created by the monk Jōin, there is clear evidence of the influence of Taisei-kyō. This becomes apparent when we compare the different ways in which Taisei-kyō's division of Shinto in Sōgen, Saigen, and Reisō was recepted in the Zen Sect and by Jōin.

Paper long abstract:

In Taisei-kyō three strands of Shinto are distinguished: Sōgen 宗源, Saigen 斎元, and Reisō 霊宗. Sōgen is another name of the well-known Yoshida 吉田 Shinto. The other two are original creations, designed to show the superiority of Buddhist Shinto.

The appearance of Taisei-kyō in the 1670s coincided with attempts that were being made in Buddhist circles to formulate a new kind of Buddhism that stressed Japan's national identity and allied itself with Shinto: the so-called Shinbutsu shūgō shintō 神仏習合神道.

Zen priests accepted the Taisei-kyo's systematisation of Shinto and paired off the three sects it distinguished with respectively exoteric Buddhism (Kengyō 顕教), esoteric Buddhism (Mikkyō 密教), and Zen. The monk Jōin 乗因（1682-1739), however, combined the Shugendō of the area of Togakushi with the Ichijitsu 一実 Shinto that was handed down in the Tendai Sect, and in this way created an original version of Shugendō, in which the Taisei-kyō's division of Shinto was received quite differently.

In recent scholarship, two interpretations exist. The first claims that the god worshipped in the Togakushi Shrine was an avatara (gongen), which would be in line with Reisō Shinto (Kobayashi Kenzō). The second interpretation is that Jōin had been influenced by the relation between state and emperor as expounded in Taisei-kyō (Sonehara Satoshi). As a study of Jōin's writings (Shugen Ichijitsu Reisō Shintō mikki 修験一実霊宗神道密記 and the recently discovered Shugendō seishū 修験道正宗) from this point of view is still lacking, I will attempt to do this in my presentation.

Next, I will contrast the different receptions of Taisei-kyō by the Zen monks and in Jōin's new Shugendō. In this way, I will attempt to show how great the influence of Taisei-kyō was in the religious thought of early-modern Japan, and how widely it had spread.