Ok...
Not all natioons are friends in UNSC. You are right, no doubt here.
My mistake of mingle friendship and UN membership. However, to support a nation joining UNSC nowadays, there will be more to consider inturns of threat, relationship gap and such. At this present time, Japan-China are not in an eye-to-eye level in turns of supporting one to become a member of global organization.
My reason of not supporting Japan joining UNSC are:
1. Intention of changing WWII history in Japan's history books in numerous instances, justifying the invasion of Asian countries using "liberation from the Western domination" as motto.
2. Denying WWII sex-slaves law suits and claims based on modern law of "statue of limitation" WWII atrocities =/= Isurance Claim (US did compensate and apologized for its mistreatment of Japanese-American during the great ware a few years ago.)
3. Refuse to apologize AS A NATION for the wrongs it created for Chinese, Koreans, Philipinos, Malays, Singaporeans, Aussies (not sure), etc (there are more Asian countries got abused). No responsibilities!
4. Racism against all froeigners in social enviornments. The westerners are being treated slight better compare to Asians (To experience this, you must live there long enough. Tourist trips ain't cut it.)
5. Low Interest LOANS, investment, and money can resolve all issues mentality. (People hear lot of Japan uses low-interest LOANs as form of compensation). LOAN = COMPENSATION...WTH! Total mentality of Money can avoid any responsibilities. Using Facade of Economic power to get sympathies from the west, yet show no sympathies to Asian neighbors on past issues.
6. Current event of issuing Oil drilling contracts to Japanese oil companies on disputed water. Now the area is in China-Japan disputed islands, not Korean-Japan disputed area. WHY IS THAT? Racism towards China? Japan targets to work with Korea with disputed islands, but not China? And is that ok?
7. Visitation of shrine by government officials with 14 Class A WWII War Criminals entombed. What do you and the world think of Germans visit Hitler and his henchmen's tombs.
Now, you can easily use Russia and China to compare with Japan's current senario. However, Russia and China are seperate issues from Japan's bid for UNSC. With today's politics, wouldn't you agree that more investigation into potential members should be promoted? If Japan could join UNSC, why don't we allow Vietname, all coutries from Africa, Cambodia, and any other coutries you think of to join the Counsel?
PS. I can only think 7 points counter Japan's bid for UNSC at this moment but I know there are more to post if time permits.