I'll try to keep it as spoiler-free as possible.
The story of a Samurai who's identity has dubious origins and later those supernatural origins become the central part of the plot, with a massive backstory that dictates the present world's fate.
Story-wise (10/10),
The story starts off with an attractive Samurai who seems obsessed with having sex with prostitutes. Later we come to know that this obsession is not exactly sexual, but rather there's a supernatural element and purpose to it, and the effects of it are very clear. That becomes central to unveiling the origins of the character and opens a deep backstory and lore that'll soon become the driving plot behind the characters' actions. In other words, the story is very progressive in its unfolding and what makes it amazing is the twists that are foreshadowed basically chapters back. One in particular is very striking because it's a bizzare non-sensical statement the character makes in the first few chapters and then suddenly it all makes perfect sense in the last few chapters. That individual Samurai you see at the beginning eventually becomes part of a millennial old God-given prophecy that will change the demographic of the world (Attack On Titan's backstory draws a lot of similarities). Throughout the entire manga, a ritual is taking place without you directly knowing it before near the end. The character is also caught between two "factions", making him an undetermined ally or enemy for a major part of the story. My only itch with the storytelling is that it can sometimes get confusing and lose track a bit.
Characters-wise (8/10),
The main character is Gen Tsukinosuke, an attractive male ronin (masterless Samurai) and there's his indirect "associate" who's a transgender woman prostitute (male who disguises a female prostitute) who's in love with Gen in a distant way (because Gen is not about that) and wants to protect him/serve him as long as he lives. The transgender prostitute is also very often portrayed masturbating while Gen has sex with women. Later, new individual characters as well as new "factions" appear. There are anti-Shogunates, Shogunates, Shinsengumi (shogunate police), beast-men, international political foreigners and the main antagonists/anti-hero. Gen is very principled and sensical in his approach, he makes for a great character to follow. The opposing forces are also well presented. My only gripe with the characters was that the beast-men were very few in numbers and very oddly integrated in social settings; you would have expected stronger reactions. Also one of the factions Gen is affiliated with are not present enough IMO, especially that they're the central "group" of the plot. That may have been by design, in order to keep us guessing more, and if it was, it worked, but it felt a little bit off when reading it.
Art-wise (9/10),
The art was very interesting. I don't know the name of that style, but it's a style you'd find in very old romance novels/books, where they tried to draw photorealistic images of people. Faces are extremely expressive and realistic.
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Sexuality and violence,
Sexuality is extremely prominent. Sex, masturbation, rape are all present in every chapter. Violence is also prominent. Head slicing, castration, infanticide/foeticide.
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Overall, a manga that slowly unfolds its deeply rich lore, slowly sneaking supernatural elements to create the world. It's raw and crude. It has a lot of similarities with Attack On Titan's lore, if that can serve as a reference. It deserves a continuation.
