Duuuh that was a brainfart on my part....
What i meant to say was instead of coming to a head over Manchuria, Russia invade Korea, the events of the Sino Japan war never occured in the timeline..
Japan and Russia were on a "collision course" over Korea, you might say. A modern Japan which seeks to be a Great Power has many needs, most of which are fulfilled by dominating (and OTL, eventually annexing) Korea (land, people, resources, strategic depth, prestige). Russia, for its part, saw Korea as a natural expansion point from Manchuria, which it devoted great effort to trying to control.
If the Sino-Japanese War never occurs (which was, in addition to a stepping stone in Japan's rise to the world stage), then it would imply Japan's still withdrawn into itself. Which, in turn, would imply further isolationism.
Full isolationism is unlikely, you realize, if only because by the 1850s, Japan was being forcibly opened up. If you have a continue of the xenophobic Sonno Joi policies, then Japan might be closer to OTL Qing China, with all that entails.