Inasmuch as one is able to find a worthy instructor and a genuine teaching, to rid oneself of fetters, and to approach the state of Buddhahood, one will inevitably be faced with seven imposing outgrowths called the three hindrances and four devils (disturbances that come in the way of Buddhist practices), just as sure as a shadow follows its source, and as clouds are present when it rains. Though one perseveres and succeeds in relieving oneself of six of the above, one would not be able to attain Buddhahood should one succumb to the seventh disturbance. I will refrain from discussing the six disturbances here. The seventh great disturbance is called the king of devils in the sixth heaven. When we, mere ordinary humans of the latter period, have completely absorbed the spirit of all the holy teachings of the Buddha’s lifetime, understood the heart of the widely acclaimed work of the Great Concentration and Insight by Grand Master T’ien-t’ai and approach Buddhahood, we nonetheless realize how difficult a task this is to accomplish. Upon the sight of one within the reach of Buddhahood, the king of devils in the sixth heaven would be stirred to say: “If one is an entity of this world, he (one) not only strives to depart from the illusion of life and death and become Buddha but also tries to lead as many as possible into Buddhism, controls this world, and transforms this defiled world into a paradise. What ought to be done?” He called together all his henchmen in the triple world, the three regions of desire, form and non-form, and commanded them: “Put each of your specialties to good use, causing trouble for that practicer (to escape the world of delusions). If it is not possible, invade the hearts of his students and believers, or of the people of his nation, to remonstrate and coerce him into giving up his practice. And if that does not work, I will go down to earth myself, penetrate the body and soul of the leader of the state, through whom I can oppress the practicer and put an end to his or her acquisition of Buddhahood.” So, in this manner, did the king of devils and his henchmen discuss.

Misawa-shō, A Letter to Lord Misawa of Suruga, Writings of Nichiren Shōnin, Doctrine 2, Page 239-240