I agree with Gabor.
Japanese customers are one of the toughest groups to deal with. One of the main reasons is that China is so close to Japan that purchasers from Japanese companies can spend a lot of time in China trading your products and prices off against other factories. So even if you are offering great quality at great prices you may find a good deal of pressure from them.
Another factor to consider is short shipping times and payment methods.
Thanks for your advice ,
Are there any breaking ways or successful euro people dealing with the japanese people ?