The Soka Gakkai Dictionary of Buddhism
kosen-rufu[広宣流布] ( Jpn)
Wide propagation, or wide proclamation and propagation. A term from the Lotus Sutra that literally means to declare and spread widely. The "Medicine King" (twenty-third) chapter of the Lotus Sutra reads, "After I [Shakyamuni Buddha] have passed into extinction, in the last five-hundred-year period you must spread it abroad widely (kosen-rufu) throughout Jambudvipa and never allow it to be cut off." Nichiren (1222-1282), identifying himself as the votary of the Lotus Sutra, made it his lifelong mission to fulfill the above injunction of the Buddha, that is, kosen-rufu. He saw widely propagating his teaching of Nam-myoho-renge-kyo, which he identified as the essence of the sutra, as the fulfillment of that mission.
Nichiren wrote in his Selection of the Time, "Can there be any doubt that, after this period described in the Great Collection Sutra when 'the pure Law will become obscured and lost,' the great pure Law of the Lotus Sutra will be spread far and wide (kosen-rufu) throughout Japan and all the other countries of Jambudvipa?" (550).
In The True Aspect of All Phenomena, he also wrote, "At the time when the Law has spread far and wide (kosen-rufu), the entire Japanese nation will chant Nam-myoho-renge-kyo, as surely as an arrow aimed at the earth cannot miss the target" (385).In On Practicing the Buddha's Teachings, he wrote: "The time will come when all people will abandon the various kinds of vehicles and take up the single vehicle of Buddhahood, and the Mystic Law alone will flourish throughout the land. When the people all chant Nam-myoho-renge-kyo, the wind will no longer buffet the branches, and the rain will no longer break the clods of soil. The world will become as it was in the ages of Fu Hsi and Shen Nung" (392). He meant that the spread of the Mystic Law would bring about peace in society and nature.