The GMMA trend in the Dow is stronger than the Nikkei trend, so there is a little more risk in the Nikkei.
Dow trend strength is shown with the long-term steady separation in the long-term GMMA.
The Nikkei trend is more volatile with two substantial tests of the long-term GMMA in April and September 2017.
Logic would suggest it's the larger market, the Dow, so Nikkei traders will watch the American index for advance indications of how the Nikkei may behave.
The Nikkei and the Dow may be joined at the hip when it comes to behavior, but the Nikkei is moving faster.