Best scenario for Japan is the highly probable loss to USA tomorrow but win ALL their remaining matches, and Brazil losing some of theirs to place 4th so Japan would face Turkey in the semifinals.
Any loss aside from USA is definitely an upset (like VNL 2019 against Herbots and BEL 🤭) but it would be probable with DOM, SRB, BEL. Two losses from this group would be a huge shame.