reselling on vacation

Hello

I am going to Osaka to visit my Girlfriend for the holidays. My bro in law sold amiibo toys for over 100 bucks from my last visit to Japan.

It blew my mind that i could make so much money on them. So i am wondering is it considered working if i sell a few things off ebay from Japan?

I respect the law of Japan so i just want to know if there are any rules i might not be aware of before i sell anything.

on a side note do you think i will having any problems going back to japan after only 5 months? i was in japan for 28 days in june - july.

I don't think selling a few items on ebay or Yahoo! auctions would constitute "working," unless you did that as business. If you are an ebay user already, you could just list the location as "(City name), Japan," and that might make it easier for those in Japan to bid? Or you could possibly ask your brother-in-law to list on your behalf?

If your last stay in Japan was for 28 days (and not 2, 3 months, I mean), I would not worry.