Lost Backpack on Hakone Tozan Railway

I have lost my backpack during my trip back from Hakone Yumoto station to Odawara Station. The train departed from Hakone Yumoto station around 830pm on 2nd March 2024. I went back to Hakone Yumoto to check with staff but he just kept telling me there was no lost backpack reported, and hinted to go back. Thus, I had to leave the station as it was already so late that there was no more train back to Asakusa where I stayed during my Japan trip. And I couldn't go back to Hakone as I need to catch a flight back on the next day.

So, I would like to seek for the help if there is any way I can continue to check or by any chance to retrieve my lost backpack?

Thanks in advance.

You can phone Hakone Tozan Railway's office (Tetsudo-bu) during 9am to 5pm weekdays at
0465-32-6823
(https://www.hakonenavi.jp/faq/#Faq)

But a railway company will keep lost-and-found items for only a week. After that, the company will transfer the item to the police station.

You can contact The Kanagawa Prefectural Police.
https://www.police.pref.kanagawa.jp/about_kpp/english/eng_inf_2.html

Or best, you can look up items by yourself.
https://ishitsu.police.pref.kanagawa.jp/find/pages/kiyaku45.html
https://ishitsu.police.pref.kanagawa.jp/find/search.do

I looked it up for you. Just in case, I typed the date starting Mar 2.
https://ishitsu.police.pref.kanagawa.jp/find/doSearch.do;jsessionid=0E...

The latest item was registered to the Kanagawa Police on Mar 7.
What you're looking for is a リュックサック. Do any of them match your description?

I have to say that if it happened to be stolen, or if it happened to be picked up by a civilian and the civilian took it to the police outside the prefecture, it may be registered elsewhere. Let's hope that the person you spoke to couldn't find it only because there was some kind of time lag between pick up and registration.