I have heard bad things about other lotteries in Japan. Like they are legally rigged in certain ways. For example, if its one of those where you reach into a box and pull out a ticket, and its held on two days, say Saturday and Sunday, its legal for them to remove the grand prize winning ticket on Saturday. Why? Because if the grand prize is won on Saturday, there will likely be low sales on Sunday.
Point being, there are laws in place, they are liable to be screwy, and you need to check them out before any conversation with police. Maybe a lawyer can help?