Yasutaka Tsutsui's "Hell" is a wonderfully surreal novel which tells the story of three protagonists and their experience with the afterlife, though for a Western audience the title is misleading, in fact, the novel's portrayal of Hell is closer to the Western idea of purgatory. In this novel, Hell is not the realm of torture for the evil, but rather a world of ambivalence. The inhabitants of Hell remember their physical, mortal lives, but they simply have no more attachments to the physical world.
The novel may be a bit culturally distant for a Western audience, as Tsutsui's work does not follow conventional Western story conventions. If you really need a good illustration of this, watch Satoshi Kon's "Paprika" (seeing as it's an animated adaptation of Tsutsui's novel by the same name), and you will get an idea of what you're up against. This novel is not something that can just be read and taken 100% literally, it requires thought, literary analysis, and a willingness on the part of the reader to step out of their own cultural norms, and just let themselves be carried away with the story.
The novel doesn't require being an expert on Japanese culture, or even knowing much about Japan at all, just the ability to look at it from a closer perspective, as though it was part of your own culture. the purpose of this is to not focus on the cultural aspects of the novel so much as focusing on the metaphysical and surreal aspects of the supernatural.
A lazy reader, or even a reader who is over-thinking the subject matter may find "Hell" to be confusing, or boring, but this is because they are looking for a definite reason for the actions which occur in the novel, and with Japanese literature, and most importantly, with Tsutsui's work, the answer often does not exist.
Not everything is meant to be comprehended, but rather just to be experienced. This is not to say that the story exists just for the sake of existing, but rather that the answers to not exist in a conventional or rational sense. You receive no definitive ending to the novel, nor do you receive any closure of what becomes of the main characters, but what you will receive, if you read this novel the way it is meant to be read, you will likely attain some form of epiphany about yourself, the life you're leading, or about the world around you.
It has been said that journalists see the world in "shades of gray" rather than in "black and white", and that being the case, this novel, as well as many of Tsutsui's other works will help you see the world "in color", metaphorically speaking.