Tokyo is changing. It used to take some 15 years of solid, profitable business performance before a company could even think about listing. I think so. The time it takes to do an IPO will drop dramatically. It already has.
Japanese people understand Japanese community best.
And it's kind of a risky market. So I'd say anyone looking into this market needs a Japanese partner or advisor. They'll help you find the targets you're looking for. In our case, after we understand your goals, we'd look on mailing lists, our personal networks, people who contact us. Then we'd help analyze the business model, and provide a solid measure of the target company.