The following review is an extract from the book "Shintaro Katsu´s Zatoichi: Complete guide to all movies", which is now available on Amazon.
In 1830, in the province of Kanto, a very powerful head of organized crime managed to unify under his command all the clans of the Yakuza. This supreme leader, whom very few have seen, controls with an iron fist illegal businesses such as gambling, prostitution and extortion; and is known throughout Japan as "The Dark Imperial Lord," or "the Shogun of the Underworld".
Zatoichi arrives in that region after witnessing numerous villagers kneeling before an outstanding character transported in palanquin: "Who is that daimyo?" He gets no answer, because it was not a daimyo, but the enigmatic "boss of bosses" and his entourage.
(...)
Together with "Zatoichi 's Pilgrimage" (Kazuo Ikehiro, 1966) this is undoubtedly one of the best episodes in the entire saga of 26 films about Zatoichi (if not directly the best). Made by Kenji Misumi, lead actor Shintaro Katsu participated in the script.
Aesthetic beauty is present throughout the film, and it is worth highlighting a scene in which the mysterious samurai chasing Zatoichi has a kind of flashback nightmare...
In the final scenes, Ichi will have to endure a real hell before confronting the sinister yakuza boss - who is as blind and cunning as he is. But unlike the "Shogun of the Underworld," Ichi is on the side of justice and always denounces hypocrisy and corruption: "We bandits act outside the law, but you behave as if you belonged to royalty..."
