They need not mimic the U.S. or the British or the French model, of course. But to qualify as a permanent member, a country should have several attributes. Japan meets the first four requirements but not the last. Germany is similar to Japan, and in fact it has begun to meet even the fifth criterion, given its recent participation in NATO military operations in the Balkans. India meets the last criterion, and most of the others as well, but its recent nuclear tests make it a poor near-term candidate because those tests violated the third reasonable prerequisite to permanent membership.
Brazil is an impressive South American power.
Nigeria may be headed toward becoming a natural candidate from Africa, especially in light of its recent progress toward democracy and its recent military efforts to quell conflict in West Africa, though it has a way to go too. The problem is twofold. First, the world community needs a fair way of determining what small group of countries should gain additional permanent U.N. Security Council seats in the years ahead. It cannot easily admit Japan or any other single country without solving the broader question first, lest it be accused of favoritism or discrimination. Second, Japan needs to broaden its security portfolio.