Information on this group is scarce; there was once an English website at http:/honmonshoshu.fujimon.org but it's been down for years.
A Japanese website is also defunct but it can be accessed through wayback:
http://www.honmonji.ne.jp/
Fortunately for the connoisseurs of obscure doctrines, I have saved much of this otherwise-lost English-language information, a small selection of which I will present to you.
This school seems to involve a generous scoop of Shinto syncretism and other theories that fall far outside the mainstream of conventional Nichiren thought. I offer it not as an advocate, but simply out of detached historical and doctrinal interest. Enjoy this unusual doctrinal smorgasbord.
The living embodiment of Aizen & Fudo Myo-ou is Nichiren Daishounin refering to Himself. That is to say, via the Kankenki, Nichiren Daishounin expresses the inner awareness of His identity as the True Buddha through outwardly expressing Himself as the living embodiment of Aizen and Fudo Myo-ou.
Aizen & Fudo Myou-ou are the 2 personas located on the left and right of the Hon-in-myou Daihonzon respectively. They are the twin Laws (of the True Buddha) that guide all existence and bring order to the world. Aizen (ie. affection) represents the Buddha Law, and Fudo (ie. immovable) is the King Law. The former is the showering of the Buddha Law. The latter deals with the delivery of that Law. The Kanjin Honzon-sho states: “When the occasions requires shakubuku, the Four Bodhisattvas appear as Wise Kings who admonish and censure foolish kings, and when it is time for shoju, they appear as Priests to maintain and spread the Correct Law.”
Dainichi Nyorai (Great Sun Tathagata) in the context of the Kankenki, is not the provisional Vairochana (“Birushana 毘盧遮那”) per se preached by the Shingon Sect. The Dainichi Nyorai (大日如来) of the Kankenki is the alternate name for Oohi-rume-no-muchi (大日霊貴). That is to say, the full title of Dainichi Nyorai is Amaterasu-oohi-rume-no-muchi-daijin (天照大日霊貴大神) which is shortened to Tensho Daijin (天照大神); the Sun God. Tensho (天照) is the alternate pronunciation of Amaterasu (天照), meaning, “Heavenly Radiance” whose symbol is the Sun with 16 rays.
The “Nichi” (日) of Nichiren (日蓮) is the same “Nichi” as Dai (Nichi) Nyorai (大日如来). Nichi (日) means Sun. Calling Himself “Nichiren” is meant to show the direct link (連 ) from Amaterasu-oohi-rume-no-muchi to Himself. In other words, Amaterasu-oohi-rume-no-muchi is the prior form of Nichiren. From Amaterasu-oohi-rume-no-muchi-daijin (ie. Tensho Daijin) to Nichiren, the transmission of Myou-hou-ren-ge-kyou is represented by the Sacred Jewel; the Divine Seal of “An-Deingiru”, the Sky God of Tenjiku (天竺).
The statement: “Nichiren confers to the New Buddha” refer to a future third manifestation of the Sun God after Nichiren Daishounin. Put together, Dainichi Nyorai (ie. Amaterasu-oohi-rume-no-muchi), Nichiren, and the New Buddha are the Three Bodies revealed in the Juryo chapter of the Lotus Sutra as the Good Doctor (Ro-I 良医), the Father (Bu 父), and Messenger (Kenshi 遣使). The same Three Bodies appear also in the Hon-in-myou Daihonzon as the “Great Awakened World Honored One” (Dai-kaku-seson 大覚世尊), the Merciful Father (Ji-bu 慈父), and Bodhisattva Jogyo (上行普蕯).
Merciful Father is of course Nichiren Daishounin. And the Messenger is Bodhisattva Jogyo.
Now, what is the meaning of the Sun mentioned here? Is it the scorching sun in the sky, or what? The Sun (ie. Nichi) is actually a synonym for the True Buddha: Nichiren Daishounin. The radiance of the Sun is the Honmon no Daimoku (ie. The Good Wave Motion) shining forth from the Sun (ie. The Life of Nichiren Daishounin in the Hon-in-myou Daihonzon).
The Good Wave Motion (Hou 法) is the vibration (ie. hadou) within fundamental mass (Myou 妙) that supports Life. It is the Excellent Medicine for the Ten Thousand years of Mappo.