日经指数的上涨现在主要与日元走弱有关吗？

That's a valid point about the JPY's impact. While exporters definitely get a boost, I've been wondering if the domestic consumer base is feeling any pinch from higher import costs, which could eventually put a ceiling on organic growth. It's a complex dynamic to untangle.

I think it's fair to say currency plays a huge role. How much of the domestic strength is sustainable if the yen were to significantly strengthen, and how would that affect the major indices?

It's certainly hard to ignore the yen's influence, almost as if the Nikkei has discovered a cheat code for export-driven growth. One has to wonder how long they can keep up the 'weak yen, strong stocks' charade before someone calls for a re-evaluation of its intrinsic value, beyond just its currency's performance.