Hard to tell what it is.
Home made, "ghost" gun, whatever. Wouldn't it be an ideal time to set up some addled dude to attempt a killing with a home made gun?
Yeah, I know, Japan, 6k miles away, but something like this would sure fit into the current PTB goals here in the US, and news is instantly world-wide nowadays. It could have happened the next town over.
Jes' spitballin', skylarkin'.