"By the Great Good of the Venerable Maudgalyayana's believing in the Lotus Sutra, not only did he become a Buddha but his father and mother became Buddhas. His father and mother and so on for seven generations up and seven generations down and for immeasurable lives up and immeasurable lives down, beyond any expectation, became Buddhas. And even children, husbands and wives, subordinates, lay donors and immeasurable beings not only left the Three Evil Ways of Rebirth but all became Buddhas from the First Abode to Sublime Enlightenment. What he worships is the Buddha Shakya; the Dharma he believes is the Lotus Sutra." -- Urabon Gosho (Letter on the Urabon)
Please note, "What he worships is the Buddha Shakya; the Dharma he believes is the Lotus Sutra" but SGI claims that Nichiren meant something else. I don't think so.