The first thing you need to do before entering into the Japanese market
The Japanese Joomla market is untapped. The word "CMS" is not known. Only big firms are using CMS. Many small and mid-size companies are still in the old age. They rely on professional web designers to create hand-made web sites.
The web site building tool like Joomla is not yet acknowledged in Japanese business circles, although blogging tools like WordPress is popular among web designers.
The overseas Joomla firms need local Japanese Joomla partners to overcome Japanese language and business practices barriers. It is important to understand Japanese users' needs and tastes.
The most difficult thing is to find Japanese clients. You are competing with local web builders and designers. If you do not have a strong sales approach, you will most likely lose the race.
Trusting new local partners is something you have to challenge. Getting to know each other well is a must. Without trust you cannot do anything in the local market.
You need Japanese friends who understand Joomla and its market. The local market information comes first. If you think it is a worthwhile challenge after evaluating its business potential, you should look for Japanese partners next.
Please do not rush! Bit by bit, learn the taste of the Japanese market and its needs. Hiring a Japanese sales person is not the answer at the initial stage, because he does not know what Joomla is and has no Joomla experience.
Please remember that Joomla is not known in Japan but people are always looking for better tools like Joomla.
In the past...
Some Joomla companies from India, Korea, and USA were trying to step into the Japanese market but they failed. I was contacted but their marketing approaches were not right. They were not following "When in Rome, do as the Romans do."
A company from India failed because they misunderstood the market conditions of Joomla. They established a joint-venture firm here in Tokyo with a Japanese system sales company. They spent a lot on advertising.
However, the market did not respond well. After one year the joint-venture firms were gone. The presence of the Indian firm is fading away from the market.
Spending lots on advertising is not the solution when the name of Joomla and CMS are not acknowledged. The best way may be grass roots marketing and the word of mouth marketing. It takes a lot of patience and persistance.
And remember... Rome was not built in one day!