It might be bad for Japan to ignore China in turn 1. If the US/UK both place IC’s in turn 1 in Sinkiang/India, Japan can’t touch them, possibly at all. By the end of turn 3, Japan will only have 2 or 3 infantry in Novosibirsk or Evenki, and the Allies could take FIB and Kwantung. The Allies could also have armor rolling north waiting for Japanese infantry columns. Japanese NP will stagnate, the Russians can deal with them easier (with US/UK IC help), Japan can’t regain south-east Asia without reducing the drive into Russia, etc.
In turn 1, if Russia takes Manchuria with fighter support and the UK builds an IC in India, Japan better keep their eyes open…