I chose this book to help prepare myself for the JLPT N1 Japanese language test. From that vantage, Fukushuu uses plenty of vocabulary and grammatical structures that will appear on the test, and is probably most appropriate for advanced readers of the language. I would suggest someone read it only if they are comfortably at the N1 level. I found myself referring to a dictionary about once per chapter, which broke the rhythm of the narrative, though was ultimately useful for my language study.
Fukushuu is a dark story of a detective who is trying to solve the murder of a fellow detective. Japanese stories in this genre tend to focus on the work of a team of detectives, meticulously obtaining clues and piecing together the crime. Detective Munesue is nothing like the lone wolf detectives of western lore. The story escapes the confines of Tokyo, and delves into areas as wide as Buddhism, the Japanese household registry system, adoption procedures, and political party structures. I found the story compelling, if not complicated, though the ending left a few strings untied. For the Japanese mystery enthusiast, especially one unafraid of dark stories, then I suggest spending time with Detective Munesue.