I got an email from YahooJP saying that I need to register a phone number that I can use in case I forgot my password and they will send the authentication code to that registered mobile number. (By the way, I am using my YahooJP ID for ebookjapan purchases - I have lots of manga there so I really don’t want to lose my account.) Since I don’t live in Japan, it’s impossible to get a Japanese phone number. For now, I just chose the option of receiving the authentication code using my other emails, but I am just worried that they might just require a phone number in every transaction. Has anyone with YahooJP account (living outside Japan) received this email as well? What did you do with the SMS authentication requirement?
Just to add some bad news. When I wanted to get a Japanese sim card, I had to prove that I lived at a Japanese address specifically (not a hotel or anything). This is mostly because Japanese sim cards use a unique frequency, which makes it quite valuable to some people (for some reason). So I think the only thing we can do is hope that they won’t require any phone numbers in the future.