According to "Nichiren, Leader of Buddhist Reformation in Japan"...The people with him started chanting "the Stanzas of Eternity" from the Lotus Sutra. Now according to the book;
"...When those who imagine that I am extinct honor my relics with great reverence, and feel sincere love for me with unbound piety and adoration, and become so gentle and devout, upright, mild, and resolute in faith, and aspire to see me heart and soul, even at the sacrifice of their lives, then I, with my train of disciples, shall reveal myself on the vulture peak, and tell them the following words: 'I am eternally here, have never passed away'....."
Quietly, gently, the weary master's eyelids closed; and he passed peacefully away.
...thou, having wisdom of it all, Shall never doubt it. Leave all uncertainty forever. My words are all true."
The book also says that his last few days were spend with his 6 senior disciples and other people, among other things, instructing them how to carry on after he passes.
"Yes, historically men have been been pillars of strength. But even Atlas shrugged. And so will you. Many times I assure you"-Barbarossa
"The other type of man, living only for himself, working only for himself, doing first one thing and then another simply because he enjoys it and because he has to keep only himself, sleeping where and when he wants, and facing woman when he meets her on equal terms and not as one of a million slaves, is rejected by society. The free, unshackled man has no place in its midst."-Esther Vilar