Nichiren Daishonin wrote this letter at Mount Minobu on the twenty-second day of the sixth month in 1275, when he was fifty-four. Its recipient, Nishiyama Nyudo, lived in Nishiyama Village in Fuji District, Suruga Province. He is generally thought to be the same person as the steward of Nishiyama Village, a man named Ouchi Tasaburo Taira no Yasukiyo. The title nyudo ("having entered the Way") indicates that he was a lay priest -- someone who has taken Buddhist vows but does not enter a temple and continues to live in the world as a lay person. One explanation identifies him as a maternal relative of the Daishonin's immediate successor Nikko Shonin, though this is not certain. In any event, he appears to have been a sincere believer who often visited the Daishonin at Minobu, bringing him various offerings.

In the opening section of this letter, the Daishonin explains the importance of "good friends," or zenchishiki -- those who can aid us in our quest for enlightenment. Because Nishiyama had previously belonged to the Shingon sect, the Daishonin used this opportunity to point out the distortions in that sect's interpretation of Buddhism. He addresses this issue from the standpoint not of doctrine, but of "the proof of actual fact," i.e., the power of religion to positively affect human circumstances.

The "three Tripitaka masters" referred to in the Gosho's title are Shan-we-wei, Ching-kang-chih and Pu-k'ung, three Indian monks who introduced the esoteric Shingon teachings to China in the eighth century. The Daishonin relates instances in which each of these men prayed for rain at the request of the throne, and in each case their prayers produced destructive gales. However, he says, prayers based on the Lotus Sutra, such as those offered by T'ien-t'ai in China and Dengyo in Japan, brought down gentle, life-giving rain.

In countries such as Japan and China, where agriculture was essential to the economy, prolonged drought could spell famine and starvation; thus prayers for rain were an important part of the people's religious life, and the ability to produce rain through prayer rituals was considered a proof of the virtue of the officiating priest and of the doctrine that he espoused. In not a few instances, disputes over the relative merits of rival teachings were resolved through prayers for rain.

After citing instances in the history of China and Japan where Shingon rituals have brought about disaster, the Daishonin further criticizes the errors of Kobo, the founder of the Shingon sect in Japan, and warns against relying on the prayers of this sect for the nation's safety. Japan at this time was facing the threat of attack by the Mongol Empire. A massive invasion fleet launched against the southern Japanese islands in the eleventh month of 1274 had been repelled by unexpected storms, but by spring of the following year, Khubilai Khan had again sent envoys demanding surrender. Anxiety gripped the country as the Kamakura government hastily organized coastal defenses, and the people readied themselves for a second attack. Quoting various sutras, the Daishonin declares that the nation finds itself in this predicament because the people rely on mistaken forms of Buddhism, while the True Law, the Lotus Sutra, is ignored or slandered.

In conclusion, the Daishonin praises Nishiyama for his sincerity, assuring him that because of his, Nishiyama's, devoted faith, he will definitely attain Buddhahood in this lifetime.