I'm not entirely sure what you mean by "Japanese momentum 50." Could you please provide more context or clarify your question? Here are a few possible interpretations:

1. If you're referring to financial markets, it could be related to the Topix 50 or Nikkei 50 index.

2. It might be about Japanese companies with strong growth momentum, possibly in a list or ranking of 50 such firms.

3. It could be related to a specific Japanese business concept or strategy involving momentum.

4. Alternatively, it might be a typo or misunderstanding of a different term.

If none of these fit what you're looking for, please provide more details so I can give you a more accurate and helpful response.