The second of the eight major hells, the Hell of Black Ropes, is located beneath the Hell of Regeneration and is the same size as it is. In this hell, the hell guards seize sinners, push them down on the ground of hot iron, make a line on the sinners’ bodies with a hot iron rope, and cut and scrape the bodies with hot iron hatchets or saw off their limbs along the line. Moreover, there are huge iron mountains on both sides of the hell. They erect iron flags on the top of each mountain, stretch an iron rope between the two flags and force the sinners to walk on the rope carrying iron mountains. Falling off the rope, the sinners’ bodies are broken into pieces. Otherwise they are boiled in iron pots. The suffering of these tortures is 10 times more severe than the Hell of Regeneration.

One hundred years in the human world correspond to one day in the Heaven of the Thirty-three Gods, the second heaven in the realm of desire, where the life span of heavenly beings is 1,000 years. If 1,000 years in this Thirty-three Heaven are equal to one day in the Hell of Black Ropes, the life span of those sinners who fell into the Hell of Black Ropes is 1,000 years.

Ken Hōbō-shō, A Clarificaton of Slandering the True Dharma, Writings of Nichiren Shōnin, Doctrine 3, Pages 107.