Inspired by
this thread:
The PoD is Oda Nobunaga surviving the attempt on his life in 1582, going on to unify Japan (or mostly, depending) and found the shogunate (or something close enough).
From there, how does Japan get to the point where it has:
1) vast economic development in the 17th Century, that creates a wealthy, independent middle class, and economy driven by (or at least heavily involved in) commerce.
2) a combination of developed (preferably crowded) urban areas and a demand for labor so high that mechanization actually saves money, giving rise to...
3) at least one factory that uses a steam engine (or something very similar) by 1750, and making them commonplace by (or before) 1800.
Bonus points if you can make this happen even faster...
(Disclosure: This is mainly to develop an idea I had with
this thread, itself somewhat ASB...)