My interpretation of NW by Murakami is that it's about the choices that a young person has to make in their life. The characters around the protagonist symbolize each one of these choices. More specifically, Naoko is about being stuck to the past and not being able to move on. Midori is about letting go and moving on from your past. The playboy character, I think was about living life without being tied to moral obligations and conventional social norms. The nerdy roommate was the opposite: he was someone very stuck on following the rules.
However, I am not sure what to make of Reiko's character. I am sure she's meant to symbolize something but I can't make out what. Maybe she symbolized throwing your life away?
by Serious_Guide_2424