The Kaidan

(iii) The Precept or Ordination Platform (Kaidan) of the Hommon (Doctrine of the Original) means the place where we receive the precepts of the Hommon and there are two types:

(1) The ideal or abstract Precept Platform (ri no kaidan) which means that wherever we receive and keep Namu Myoho renge kyo is the Precept Platform. It does not point to a special place and building and its rationale is found in Chapter 21 of the Lotus Sutra:

"Those who receive, uphold, read, recite, explain, write out, and cultivate it as spoken, in whatever land they may be, in a place where the Sutra is kept: whether in a garden, in a forest, or beneath a tree; in a Sangha dwelling; in the dwelling of the white-robed; in a palace or hall; or in the mountains, valleys, or wilderness in all of these places they should build a stupa and make offerings."

(2) The Actual Precept platform (ji no kaidan) means that, in the future, a particular place will be established by "the ruler", the Precept Platform of the Doctrine of the Original. (Nichiren Daishonin did not decide on the place but if it should return to the pure doctrine and practice, We find the rationale for the Actual Precept Platform in Chapter 16 of the Lotus Sutra:

"Good men, if a living being comes before me, I observe with my Buddha eye his faith and other qualities, as well as the keenness or dullness of his faculties, and I take him across in an appropriate manner."

and

Living beings, then faithful and subdued,
Straightforward, with compliant minds,
Single-mindedly wish to see the Buddha,
Caring not for their very lives.
At that time I and the Sangha assembly
All appear together on Magic Vulture Mountain, 

The Three Great Secret Law Gosho states:

"As for the Seat of Ordination [kaidan], the Law of the Sovereign and the Law of the Buddha are united and become one, and sovereign and subjects become one in their faith in the doctrine of the Great Three Mysteries, the same bond that existed in the days of old between King Utoku and the Monk Kakutoku will also exist in the future world of the impure and evil Age of the Latter Law."

Therefore, according to Nichiren Daishonin, the place where a faithful sovereign chooses to enshrine the Object of Worship (Honzon) of the Original Doctrine [where the Master of Teachings Buddha Shakyamuni who attained Buddhahood in the limitless past dwells], is the Actual Precept Platform.