Nichiren … emphasized that whenever ordinary men and women accept and keep the Sacred Title, the Four Great Bodhisattvas, including Superb-Action, will unquestionably appear to protect them. Since the Sutra defines these Four Great Bodhisattvas as “the highest leaders among people,” they are destined to lead all living beings. Apparently Nichiren saw these Bodhisattvas as symbols of his own position as leader of the people. He stated this in his work, Shohojisso-sho, “The Real State of All Things.”
Born in this Age of Degeneration, [Nichiren] presents and propagates the Wonderful Dharma (the Sacred Title) prior to the appearance of Superb-Action Bodhisattva, who is initially assigned to propagate it … This is a glorious thing to me. … It is only Nichiren who is ahead of the Bodhisattvas from Underground in performing the mission given by Sakyamuni. In this sense, [Nichiren] may also be counted as one of the Bodhisattvas from Underground (who are authorized to lead living beings in the Age of Degeneration).
Introduction to the Lotus Sutra