Update: Dec 2018 - there now seems to be a good option, checkout One fund to rule them all?
Perhaps I was looking for a specific solution to a general problem, a better question would have been this:
What is a simple, tax-efficient, globally diversified stock portfolio suitable for investing at a Japanese broker?
Preferably it should be suitible for all of iDeCo, NISA, and Taxable (tokutei) accounts.
The guidelines given the products currently available seem to be:
- Use Japan-domiciled investment funds (投資信託), and as a rule avoid dividend-paying ETFs, especially foreign-listed ones, or funds that wrap them.
- Use a mixture of 3 low-cost funds: Japan, Developed Markets Ex Japan, and Emerging Markets.
- A Rough guide for asset allocation based on MSCI ACWI Index is Japan (8%), Emerging Markets (12%), Developed Markets (80%).