How do I become a japanese citizen

I am a "nissei" second generation I was born here in california
I want to retire in okinawa japan in the near future if possible

Are you sure that you aren't already a Japanese citizen? Your parents never registered you at the Japanese embassy?

Consult your nearest Japanese Embassy or Consulate- they are the experts on this kind of thing.

My parents never registered me in the japanese embassy will this be a problem ? Even though I was born and raised here in california ?

you should be able to because one of your parentes is japanese. but like others say, if your parentes did not register you before you became 20 years old, Japanese governement more likely will give you a hard time.. i imagine.

Unfortunately it's not simple when it comes to citizenship issues in Japan. As Sira said, just contact your local Japanese embassy and go for a straight answer rather than speculating with non-experts. The folks in Downtown LA are really helpful and knowledgeable especially if you speak Japanese.

If you haven't done so already, you should read the Nationality Law:

http://www.moj.go.jp/ENGLISH/information/tnl-01.html

I don't think you qualify for citizenship unless you're under 20. But don't worry, you can still retire in Okinawa. You can get the Child of a Japanese National visa. You're not required to have a job under this visa if you have sufficient funds.

What is a child of a japanese national visa ? Would that be me even though I am a 45 year old or a child of my own which I do not have

An adult can be a "child of a Japanese national" for visa purposes.It means that one of your parents is/was a Japanese national. It allows you to live and work in Japan without restrictions, although it must be renewed each time it expires so is not permanent residence.

Again, the embassy/consulate can tell you everything you need to know regarding this topic, and can provide you with the documents you need to start the process as well.