I'm curious though, why doesn't his vest say 警察
From the pictures I've seen, it's not there, just a white POLICE label on the back and yellow unit numbers on the helmet although Paul's answer did make me chuckle

Also, there's no way I'm even going to attempt painting that on a 28mm figure. When I do the normal police (koban) I might see about getting some relevant decals done

cheers
James