Maybe there was a major misunderstanding somewhere.
In general, if at all possible, I think it's best to tell the police (or staff members of whatever facility you happen to be inside) when there's an object that does not belong.
My experiences with the Japanese police:
1. I once found a wallet and carried it all the way to a nearby police box. Had to fill out some forms but no problems.
2. Another time I found and captured a dog running around town and had the police come to fetch it. Again no problems.
3. Just today while renewing my driver's license, I had some time before the lecture started so I walked out of the classroom and searched for a vending machine. I probably looked like I was a bit lost, and a police officer asked me what was wrong.
- Anyway - The plural of anecdote isn't data but I've only had nice encounters with the Japanese police so far.
(1) was in Hadano (Kanagawa), (2) was in Matsue (Shimane), (3) was in Nagoya.
Thinking back I left out a couple encounters.
4. Asked the police box staff if they knew how to get to my hotel (this was before smartphones were common), they helped me (Tokyo)
5. Filed a lost item report (my wallet was stolen, in Japan!) (Tokyo). Didn't turn up (duh) but I think I needed a piece of paper to get back my teikiken on my Suica card.
6. Filed another lost "item" report (a dog I was taking care of ran off. Man, that was nerve-wrecking). They actually helped me look for the dog I think! (No relation with the dog incident in Matsue.) (Shounan region, Kanagawa prefecture)
7. I was cycling to work and it was raining. I was holding an umbrella in one hand and a police car passed by and they used their loudspeakers to tell me to close my umbrella (but didn't stop me or anything). This was in a rather rural area of a rural town (Matsue). I think this is a recently introduced law -- someone holding an umbrella while cycling bumped? crashed? into someone and actually killed them. :/
8. Apparently police box officers walk around the neighborhood ringing on every doorbell and asking if anything's been up lately. That happened in Nagoya a couple weeks ago. I liked it.
My experiences with the Japanese police:
1. I once found a wallet and carried it all the way to a nearby police box. Had to fill out some forms but no problems.
2. Another time I found and captured a dog running around town and had the police come to fetch it. Again no problems.
3. Just today while renewing my driver's license, I had some time before the lecture started so I walked out of the classroom and searched for a vending machine. I probably looked like I was a bit lost, and a police officer asked me what was wrong.
- Anyway - The plural of anecdote isn't data but I've only had nice encounters with the Japanese police so far.