Shimotsuma Rairyō served as a bushō from the Sengoku to early Edo periods. He was born as the eldest son of Shimotsuma Rairen, a priest at the Ishiyama-Hongan Temple. His childhood name was Chikafuku and he was commonly known as Mimasaka-no-kami.
From 1575, he served as an assistant to Kenson, the abbot at the Kōshō Temple who was the second son of Kennyo, the high priest of the Ishiyama-Hongan Temple. During the Ishiyama War during which adherents of the temple engaged in a prolonged struggle against Oda Nobunaga from 1570 to 1580, Rairyō supported Kenson by communicating orders to the temple followers. After the war, in 1581, he was appointed as a senior monk. In 1601, he adopted the name of Sōha, and, in 1627, served in the Nishi-Hongan Temple. Thereafter, his whereabouts are unknown. His son, Rairyō, served in the Higashi-Hongan Temple.