SHIT, how did I miss this. Mercari JP is allowing BTC use as of this month:
https://cointelegraph.com/news/japanese-e-commerce-giant-mercari-allow-bitcoin-payments-june
"Mercari is one of Japan’s largest consumer-to-consumer e-commerce marketplaces, with 22 million monthly users. The marketplace was launched in 2013 and, in five years, became the largest community-based e-commerce platform in the country, with a 94% usage rate ... Mercari will allow users to purchase its flea market app-listed products using Bitcoin starting in June."