When you have a 6 month visa, you fly to Japan and stay for a week. When you fly back to Thailand, does the 60 days start over?
TLDR : Answer Summary
Yes, if you hold a 6-month multiple-entry tourist visa, you will receive a new 60-day stay upon re-entering Thailand after flying to Japan for a week. Additionally, you can extend this stay for another 30 days, allowing for a maximum of 90 days for each entry.