CommentStreams:212eda137d4ae41605a93d9ac1f8e50b

Having a bit of a dig through the japanese wiki article, it would appear that the police donating it is speculation, not actually a fact. It also appears that despite it being in the National Film Center, no-one seems to be able to access it despite many trying.

This is a shame, if you've seen any of Hakusan's other animation it is truly wonderful. He really needs to have his legacy preserved, even if it was a bit cheeky.