What does this peculiar Japanese DNS arrangement signify - ocn.ne.jp.spam?

I have been receiving spam emails on my many mails but specifically gmail from a .jp domain. I noticed the email was from a Japanese domain and I decided to follow the top level domain.

I went ahead and opened ne.jp and that redirected to The page reads: About www.ne.jp

The name of this domain is www.ne.jp, NOT ne.jp. Japanese domain names, like those of many countries other than the United States, consist of three parts rather than just two (compare a typical American domain like "aol.com"). We just happened to register the word "WWW" as the private part of our name -- the Japanese equivalent to the US domain www.net. In other words, the "WWW" part is not simply an indicator of where the home page resides, as in most cases, but is actually the name itself.

Thus, if you are searching for information about a domain name of the form foo.bar.ne.jp, where bar is not "WWW", you've come to the wrong place. In particular, if someone has attacked you or spammed you from such a domain, it has nothing to do with us. You can find more information about the real culprit by looking up the name bar.ne.jp in the WHOIS database at JPNIC, the Japan Network Information Center.

From the page, ...In particular, if someone has attacked you or spammed you from such a domain, it has nothing to do with us.

Why do they say that while the mail outpost@alpha.ocn.ne.jp is part of ne.jp?