I really enjoy Banana Yoshimoto's writing and have read a few of her other books as well (Kitchen and Asleep; Lizard is on my to-read list). She has a way with weaving the simplest language into a world that revels in the magical realism of everyday life.
NP is about the relationship that forms between four people who are all connected in some way to the writer Sarao Takase and his untranslated collection of stories entitled "NP" (North Point). I felt like this novel focused a lot more on despair and dysfunctional relationships than her other stories that I've read do (for example, a significant plot point is the incestuous relationship between Sui and Otohiko, and the incestuous relationship between Sui and their father, Sarao Takase). The narrator finds herself totally entranced by these people and their personalities, not to mention the fact that they are all bound by a common knowledge of Takase's work and are intimately tied to it through death; the narrator's boyfriend, who was working on translating the book, committed suicide, as did Sarao Takase. There really isn't a whole lot to the plot aside from the deepening connection between the characters, which unfolds over the course of one summer. It ends with the suggestion of new beginnings, and it seems that the characters are able to escape their "fate" as mere characters within their father's stories.
One of the things I found interesting about this book is the discussion of language, translation, and the connection to one's country. All of the characters except the narrator have spent extended amounts of time living in the US, and moved back to Japan only after their father died (he wrote his stories in the US, in English). Even though the narrator hasn't shared their experience of living in another country, she nonetheless shares their experience of knowing the world through both English and Japanese, and works as a translator just as her mother does and deceased boyfriend did. As a child, she also lost her voice for a while and describes how she began to interpret the world in colors rather than words. Considering the devastating effect that Sarao's stories had on his children, along with the many references to language and problems with translation, I think it's safe to say that this book is not only about language, but how language functions as an intimate, integral part of our lives and has immense power in shaping us. But language is fluid; it can be many different things to many different people, and one language doesn't simply and straightforwardly translate into another...in a way, everyone has his or her own language.
On the downside, I felt like the only character who was really well-rounded was Sui, although she is actually the last character to be introduced into the story. Even the narrator seems a little hollow. I feel like the characters were so defined by their relationships to one another that I have a difficult time describing them as individuals (but maybe that was the point).