Buying a bicycle off someone on Facebook?

I see a lot of sellers on Facebook selling used peddle assist bicycles for about 50,000 yen, some are titled fujichari. Does anyone have experience with any of these sellers? Seems to be foreigners and it looks like they obtain many bicycles and fix them to resell. I see some Yamaha PAS and bridgestones.

I'm being offered a bicycle and the person is saying they will deliver, cash on delivery and will give me paperwork to register at the local Koban. Just trying to make sure I'm not being scammed in some way such as the bicycle falling apart on me immediately or it being stolen.

by SuperFriends001