I’ll put this here for anyone else running into the broken service page.
The address given for support is the following:
Yamaha Music Japan Co,Ltd
Unfortunately, this goes back to the Steinberg website, which has a broken service page. They were also nice enough not to include any other method of contact.
Googling for “Yamaha Music Japan Co, Ltd Takanawa, Minato-ku 2-17-11” I got their 2015 exhibition page, which lists a different website.
Going to that page and selecting Japan as the region (since that is my “local” support), I am brought to this page.
Note that the following makes use of Google Translate built into Chrome to navigate the pages.
In the top right, there is a button for support.
They then recommend making an inquiry by e-mail (web form).
In the middle, there is a button for inquiries about AV, music production equipment, PA, and other products, which includes Steinberg products.
Clicking on the “inquiry via e-mail (web form)” link here will result in a loop. Instead, this time you have to scroll down and click “Steinberg Products” which opens up and shows a Contact Us button.
Most of the contact page is reasons why Yamaha won’t help you. Ok fine, scroll past all that to the Check the above contents and contact us link with the nice little check mark.
Not there yet. More reading to do. First, they make sure you read the extensive list on the previous page for reasons you shouldn’t expect support.
But if you are really really sure you want support, then click the Inquiry by email button in the middle of the page.
Finally, you can write your message to support.
Note that the FAQ: Free update to latest Cubase AI Cubase LE version for all registered users page is only available in English, German, Spanish, French, and Italian. So it’s possible Yamaha Japan will not honor the upgrade because it’s not written in Japanese.