I found a recent paper from the Singapore Management University...

I found a recent paper from the Singapore Management University that studied short selling in Japan.
On the last page it lists the large institutions that held short positions (in millions of Yen). MUFG and Morgan Stanley are well up on the list.
The content is enlightening, although I would need to reread it a few times to understand it properly but it details a lot about how the shorting is managed by the larger firms.

Anyway I think I am going to be wary for a while until I see which way the SP moves with this lot in play. It may end up as a chance to accumulate more later if the SP drops.

All IMHO only and DYOR.