Who is the one who expound the Lotus Sutra as referred in the sutra?

The sutra states: "If one [of these good men or women in the time after I have passed into extinction] is able to secretly expound the Lotus Sutra to one person, even one phrase of it, then you should know that he or she is the envoy of the Thus Come One. He has been dispatched by the Thus Come One and carries out the Thus Come One's work." Who else but us can this possibly refer to? 17/5

The Writings of Nichiren Daishonin
The True Aspect of All Phenomena
Written to Sairen-bo Nichijo on May 17, 1273