Rakuten is a great site and if I don’t see the shit I need in the U.S. shops, or if none of them got the size I need, I usually just order directly from a Rakuten store. (and if none of the Rakuten stores that ship to U.S. got the shit I want, it becomes a problem and I would have to find a forum member doing pickup service in Japan, or use celga, juno, or spe)
Anyway, when you create an account at Rakuten they automatically subscribe you to their mailing list. There might’ve been an option to opt-out during registration but since I don’t read Japanese I didn’t want to risk checking off checkboxes I don’t understand what they were for. I just got another email and at the bottom there was a link to unsubscribe:
Click on that link will bring you to a page with 2 links, it looks like this:
Click on the second link, it will then bring you to a page with a bunch of checkboxes, don’t check or uncheck any of them, just click on the submit button at the bottom. This should unsubscribe you to their newsletters.