Shōnyo was a monk in the Jōdo-Shinshū sect during the Sengoku period, or the True Pure Land School of Buddhism. Shōnyo served as the tenth high priest of the Hongan Temple as well as the tenth head of the Ōtani branch of the Jōdo-Shinshū sect. He was the abbot of the Yamashina-Hongan Temple in Kyōto and the great-grandson of Rennyo, the eighth high priest of the Hongan Temple.
On 12/23 of Eishō 13 (1516), Shōnyo was born as the son of Ennyo from the Henzō Temple. His mother was Keijun Chineini.
In 1525, after the death of Jitsunyo (Shōnyo’s paternal grandfather and ninth high priest of the Hongan Temple), he succeeded him, at the age of ten, as the tenth high priest of the Hongan Temple. Owing to Shōnyo’s young age at the time of succession, Renjun (Jitsunyo’s younger brother and Shōnyo’s maternal grandfather) served as his guardian.
In 1527, to deepen ties and promote tranquility between the religious band of the Hongan Temple and the central authorities, Shōnyo became a yūshi, or a child considered as one’s own, to a noble named Kujō Hisatsune, the kanpaku, or Chief Advisor to the Emperor. Subsequently, he entered the priesthood under the tutelage of Prince Sōchinhō, the younger brother of Emperor Gonara.
In 1531, a conflict arose among the followers of the Hongan Temple, an event known as the Kyōroku Disturbance. Shōnyo suppressed the disturbance and thereby strengthened his leadership as the high priest of the temple.
In the sixth month of 1532, upon the will of Renjun who, in turn, was subject to demands from Hosokawa Harumoto, Shōnyo mobilized the monks and launched a surprise attack against Miyoshi Motonaga (of the Hokke sect) while he sojourned in Kawachi Province. The monks chased and killed him in Izumi Province, but those monks engaged in uprisings continued to rampage, forcing their way into Yamato Province. Wielding destructive power beyond the original purpose, the Ikkō-ikki were capable of turning in the direction of the capital. This posed a threat to Harumoto so, in the seventh month, he parted ways with the Hongan Temple and joined forces with the followers of the Nichiren sect and Rokkaku Sadayori. On 8/24 of 1532, this contingent assaulted the Yamashina-Hongan Temple in Kyōto (the main base of the Hongan Temple) and burned it down in an event known as the Battle of Yamashina-Hongan Temple. After being driven out of the temple, Shōnyo moved his residence to a monastery in Ōsaka called the Ōsaka-Hongan Temple, establishing this site as the base for a new religious band.
Later, Shōnyo arranged for his eldest son, Kennyo, to become engaged to the adopted daughter of Harumoto (Kyōkōin Nyoshunni, the third daughter of Sanjō Kinyori, a noble and the Minister of the Left Division) and he reconciled with Harumoto. Shimotsuma Raisei, as a member of the warring faction, was demoted. Raisei and his older brother, Shimotsuma Raishū, then departed from the Hongan Temple. In 1536, Raisei was killed in the bustling harbor town of Sakai by an assassin sent by Shōnyo. In 1539, Raishū was killed in Ōmi Province, also by assassins said to be sent by Shōnyo.
Shōnyo endeavored to foster close relations with the Muromachi bakufu and restore relations with the central authorities, reinforcing the foundations of the Hongan Temple. As a lesson from the Battle of Yamashina-Hongan Temple, he further ordered the Ikkō-ikki in each location not to trigger indiscriminate disturbances.
In 1546, he built the Oyama monastery in Kanazawa in Kaga, reinforcing his control over the community of monks. Owing to conflicts with the Asakura clan, however, in the era of Shōnyo, this control was not fully attained. Through mediation of the Kaga Ikkō-ikki, he deepened his intervention in the affairs of the band of monks in the Hokuriku region.
In 1549, Shōnyo received from Emperor Gonara a collection of waka, or classic poems, by thirty-six well-known composers from the late Heian period. Later, in the era of Kennyo, there was an attempt to give the work as a present to Konoe Sanehisa, a regent, for promoting a settlement to the Ishiyama War, but he refused the offer, stating “You should not exchange a treasure from heaven.” These manuscripts remain at the Nishi-Hongan Temple and are designated a national treasure. That same year, he was appointed Provisional High Priest.
On 8/13 of Tenbun 23 (1554), Shōnyo died at the age of thirty-nine. He was succeeded by Kennyo who, at the age of twelve, became the eleventh-generation high priest of the Hongan Temple.