The Lotus Sutra in personified terms

"Nichiren regarded the words of the Lotus Sutra as the expression of Śākyamuni Buddha’s mind and—based on the logic of the nonduality of form and mind— asserted that the Lotus Sutra is none other than Śākyamuni Buddha and that Śākyamuni Buddha is precisely the Lotus Sutra. Herein we can discern the reason why Nichiren often refers to the Lotus Sutra in personified terms. This is especially important to bear in mind when we consider his understanding of the object of worship of the origin teaching as both the Lotus Sutra and the primordially awakened Śākyamuni." -- Kitagawa

Specifically, Shakyamuni Buddha in personified terms is the Lotus Sutra and generally, those who chant Namu Myoho renge kyo with the same faith as Nichiren are the Lotus Sutra:

"In essence, the entity of Myoho-renge-kyo (Lotus Sutra) is the physical body that the disciples and followers of Nichiren who believe in the Lotus Sutra received from their fathers and mothers at birth." - The Entity of the Mystic Law. 

"If you confuse the general with the specific even in the slightest, you will never be able to attain Buddhahood" - Nichiren