This is a very broad question and depends on the product or service. Japan is a land of vertical supply side integration - so most import b2b products need to have an extreme case of design improvement / price competition in order to succeed.

If you are a service business - as long as you can adapt to the japanese consumer with japanese design and utility sense - you should be able to market successfully.

There are some markets which are increasingly becoming attractive for foreign suppliers - such as the healthcare market - due to the single payer system and the need for cost improvement.