This is the most well-written manga I have ever read. The premise/summary might turn you away, but if it does, then you are missing out on a masterpiece.
This 4 volume manga is incredibly intense, and the story-telling is unbelievable. The buildup from the first 2 volumes explodes into all out chaos in the 3rd, and the 4th volume provides one of the most satisfying and well-written endings you will ever come across. If I had one complaint, it would be the lack of other titles by this author, because this level of story-telling is one that I have yet to see in other mangas.
The character evolution is mind-boggling, and the first person narrative really puts you into the mind of the male lead. As the description says, this manga truly shows the worst and best of the human condition. Instead of resorting to cheap acts and exaggerations to illustrate human cruelty, the author cleverly shows the cruel effect daily situational occurrences can have on the main characters. Although the story is at times soul-crushing, it is eventually able to lift the characters out of their seemingly endless spiral, and the ending could not be more heart-warming. That, in my opinion, is the best part of this awesome manga.
The art is not perfect, the premise is a turn off, but give it a chance and you will be surprised. Onani Master Kurosawa is an unbelievable story of weakness, strength and redemption that will make you think, feel and ultimately smile.