Nichiren's teachings on the Three Treasures of Buddhism Regarding the Buddha

"...the Nirvana Sutra states: “If there are those who possess differing ideas concerning the three treasures, then truly you should know that these people can no longer hope to take refuge in, or rely upon, the three pure treasures. They will never gain benefit from any of the precepts, and in the end, they will fail to obtain the fruits of the voice-hearer, the cause-awakened one, or the bodhisattva.” - The Third Doctrine

He states also:

"The fourth is the debt owed to the three treasures. When the Thus Come One Shakyamuni was engaged in bodhisattva practices for countless kalpas, he gathered all of the good fortune and virtue he had gained thereby, divided it into sixty-four parts, and took on their merit. Of these sixty-four, he reserved only one part for himself. The remaining sixty-three parts he left behind in this world, making a vow as follows: “There will be an age when the five impurities will become rampant, erroneous teachings will flourish, and slanderers will fill the land. At that time, because the innumerable benevolent guardian deities will be unable to taste the flavor of the Law, their majesty and strength will diminish. The sun and moon will lose their brightness, the heavenly dragons will not send down rain, and the earthly deities will decrease the fertility of the soil. The roots and stalks, branches and leaves, flowers and fruit will all lose their medicinal properties as well as the seven flavors. Even those who became kings because they had observed the ten good precepts in previous lifetimes will grow in greed, anger, and foolishness. The people will cease to be dutiful to their parents, and the six kinds of relatives will fall into disaccord. At such a time, my disciples will consist of unlearned people without precepts. For this reason, even though they shave their heads, they will be forsaken by the tutelary deities and left without any means of subsistence. It is in order to sustain these monks and nuns [that I now leave these sixty-three parts behind]. - the Four Debts of Gratitude

Even if we should gather all the water of the four great oceans to wet inkstones, burn all the trees and plants to make ink sticks, collect the hairs of all beasts for writing brushes, employ all the surfaces of the worlds in the ten directions for paper, and, with these, set down expressions of gratitude, how could we possibly repay our debt to the Buddha?" -The Four Debts of Gratitude

Number one is debt and gratitude to the Buddha Shakyamuni. With a different Three Treasures you just won't get it, not to mention, adding to the disunity. Nichiren sought to establish pre-sectarian Buddhism, modeled after the Buddhism in the Former Day where monks and nuns, laywomen and laymen all worshipped the same Three Treasures. Those who believe in Nichiren as the Original Eternal Buddha are sectarians who don't even follow the very clear mandates of their True Buddha.

"The Treatise on the Treasure Vehicle of Buddhahood by Bodhisattva Sāramati reads: “Those who are ignorant and unable to believe in the correct teaching, who hold false views and are arrogant, suffer such hindrances in retribution for the slanders of their past lives. They cling to incomplete doctrines and are attached to receiving alms and being treated with deference; they recognize only false doctrines, distance themselves from good friends, approach with familiarity such slanderers who delight in attachment to the teachings of the lesser vehicle, and do not believe in the great vehicle. Therefore they slander the Law of the Buddhas.

“A person of wisdom should not fear enemy households, snakes, the poison of fire, the god Indra, the roll of thunder, attacks by swords and staves, or wild beasts such as tigers, wolves, and lions. For these can only destroy one’s life, but cannot cause one to fall into the Avīchi hell, which is truly terrifying. What one should fear is slander of the profound teaching as well as companions who are slanderers, for these will surely cause one to fall into the frightful Avīchi hell. Even if one befriends evil companions and with evil intent spills the Buddha’s blood, kills one’s own father and mother, takes the lives of many sages, disrupts the unity of the Buddhist Order, and destroys all one’s roots of goodness, if one fixes one’s mind on the correct teaching, one can free oneself from that place. But if there is someone who slanders the inconceivably profound teaching, that person will for immeasurable kalpas be unable to obtain emancipation. However, if there is one who can cause others to awaken to and take faith in a teaching such as this, then that person is their father and mother, and also their good friend. This is a person of wisdom. After the Thus Come One’s passing, that person corrects false views and perverse thoughts, and causes people to enter the true way. For that reason, he has pure faith in the three treasures, and his virtuous actions lead others to enlightenment.”

Bodhisattva Nāgārjuna states in his Treatise on the Discipline for Attaining Enlightenment: “The World-Honored One expounded five causes3 leading to the hell of incessant suffering. . . . But if, with respect to the profound teaching that one has yet to comprehend, one were to remain attached [to lesser teachings and declare that this is not the Buddha’s teaching], then the accumulated sins of all the above-mentioned five acts would not amount to even a hundredth part of this offense.”

A wise person, while dwelling in security, anticipates danger; a perverse one, while dwelling amid danger, takes security for granted. A great fire fears even a small quantity of water, and a large tree may have its branches broken by even a small bird. What a wise person fears is slander of the great vehicle. It was on this account that Bodhisattva Vasubandhu declared that he would cut out his tongue,4 Bodhisattva Ashvaghosha implored that his own head be cut off, and the Great Teacher Chi-tsang made a bridge of his own body.6 The Tripitaka Master Hsüan-tsang traveled to the sacred land of India to discern [which teaching represents the truth], the Tripitaka Master Pu-k’ung likewise returned to India to resolve his doubts, and the Great Teacher Dengyō sought confirmation in China. Did not these men act this way in order to protect the true meaning of the sutras and treatises?" - The Problem to be Pondered Night and Day

"Answer: The Benevolent Kings Sutra says: “Those persons who should uphold and guard the three treasures of Buddhism will on the contrary become the destroyers of the three treasures, just as it is the worms that are born from the body of a dead lion that will feed on the lion’s flesh. It will not be the non-Buddhists [but in most cases the Buddha’s own disciples who will destroy this Buddhist Law of mine].” - On Dealing with Disaster

“The Buddha said to Shāriputra, ‘No, they are not similar. Why is that? Because if one destroys the perfection of wisdom, then one destroys the all-inclusive wisdom and the wisdom that understands every aspect of phenomena possessed by the Buddhas of the ten directions. When one destroys the treasure of the Buddha, then one destroys the treasure of the Law, and when one destroys the treasure of the Law, one destroys the treasure of the Buddhist Order. When one destroys the three treasures, one destroys all the correct views in the world, and when one destroys all the correct views in the world, then one is committing a crime that will bring one unlimited retribution. And when one has committed a crime that will bring unlimited retribution, then one must undergo pain and suffering for an unlimited period of time.’” - What it Means to Slander the Law.

I won't even get to the destruction of the Third Treasure, the Order headed and exemplified by the priest Nichiren. I guess you weren't hungry (in SGI). You ordered half the order (without priests). Nichiren wrote to dozens of priests, praising them and cited dozens of priests who confirmed his doctrines. 

"Look carefully at the present situation. Is it due to the offense of slandering the Lotus Sutra, or is it punishment for belittling Nichiren, or is it because of the great offense of slandering the three treasures—the Law, the Buddha, and the Order? Because of these circumstances, in their present existence these people have brought the world of asuras into this country, and in their next existence they will without fail fall into the hell of incessant suffering." - Reply to the Honorable Konichi

"All of this came about because they put their trust in the True Word and Nembutsu teachings and acted as implacable enemies of the Lotus Sutra and Shakyamuni Buddha. Because they did so, they were cast aside by the Sun Goddess, Great Bodhisattva Hachiman, and the other deities of heaven and earth, and by the three treasures of Buddhism in the ten directions. While alive, they were attacked by those who should have been their followers, and after death, they fell into hell." - Condolences on a Deceased Husband.

Nichiren Honbutsuron (Eternal Buddha) is nothing but founder worship for the arrogant people of Japan who Nichiren called the most evil people of Jambudvipa.

"Next, the four debts of gratitude of Buddhism are (1) the debt of gratitude to be paid to one’s father and mother; (2) the debt of gratitude to be paid to the ruler of the nation; (3) the debt of gratitude to be paid to all living beings; and (4) the debt of gratitude to be paid to the three treasures [the Buddha, the Law, and the Order]. - The Four Virtues and the Four Debts of Gratitude

"The karma incurred by the committing of any one of these offenses will last for the space of a single lifetime. Therefore, if as a result one falls into one of the evil paths of existence, one will not fall into the evil paths a second time. But the karma incurred by slandering the Law lasts for many lifetimes. Therefore, if one once acts in a manner injurious to the three treasures of Buddhism, one will again and again be reborn in the evil paths." - The Diagram of the Four Periods

Replacing Nichiren for Shakyamuni Buddha and Nikko for Nichiren, one has injured the Three Treasures of Buddhism.

Lastly, from the Rooster Diagram of the Five Periods Page 1039 and down, nothing could be more clear regarding the Treasure of the Buddha:

And from the Rooster Diagram of the Five Periods:

“If it were possible for one Buddha to take on the identity of another Buddha, that would mean that the first Buddha is capable of effectively propagating the teachings of the second Buddha. And if, conversely, the second Buddha could assume the form of the first Buddha and spread his teachings, it would mean that he could take over the task of leading to enlightenment those who had formed a bond with the first Buddha. But the beings who were being led and trained by these Buddhas, failing to understand all this, would become completely confused as to who was their true teacher and with which of the two Buddhas they had formed a bond." -

and further down from page 1039 and down:

In the final Diagram, the Eternal Buddha of the True Tientai school:
"The Object of Devotion
the Thus Come One Shakyamuni as the Buddha who actually carried out practice and achieved enlightenment in the inconceivably remote past
Vairochana of the Flower Garland school, Mahāvairochana of the True Word school, and other Buddhas are all followers of this Buddha.
Three bodies attained in the remote past
manifested body... has no beginning, has no end
reward body... has no beginning and no end
Dharma body...has no beginning and no end

"The Treatise of Five Hundred Questions states: “If a son does not even know how old his father is, he will also be in doubt as to what lands his father presides over. Though he may be idly praised for his talent and ability, he cannot be counted as a son at all! It is like the age before the Three Sovereigns, when people did not know who their fathers were but all lived like birds and beasts.”