I'm a permanent resident and I don't think I'll bother with becoming a Japanese citizen as I don't want to give up my own nationality and passport. Japan doesn't allow dual citizenship (last time i checked) and I don't see any extra benefit to myself or Japan by jumping though the hoops of becoming a citizen. It may be something that others want but not me. It is possible and one does not have to be famous or a sports star. David Aldwinkle has a lot of advice on this but I think it best not to post too much. Perhaps people can Google if interested.
PS: If a persons request for citizenship is declined there is no ownus on the Japanese government to explain why it was declined.