I've only seen one post so far showing in detail how long it took for them to receive their passport, etc., so I wanted to add-on for anyone else who may be wondering.
I still had a year left on my passport but because I'm going to be applying for another visa soon for work here, I figured it'd be better to do it now rather than later and get an extra 10 years on the passport before the next time.
I sent it in by mail, didn't want to bother going in person.
The materials needed are on this site
For the photo, I saw some people saying a blue background was fine, but to just eliminate any issue I paid the ¥1000 at one of the Fujifilm 証明写真機 and cut it to size with a white background.
The return envelope can just be folded and put into the main envelope being sent to the embassy along with everything else.
Gathered and sent by mail – 8/27
Arrived at Tokyo Embassy – 8/29
From then I had two tabs open on my phone.
One for the original envelope tracking お問い合わせ番号 sent to the embassy and the second tab for the tracking お問い合わせ番号 of the return envelope.
I received notification on the second tab of Japan Post and the return envelope was sent out – 9/17
Renewed passport received – 9/18
Total of 21 days.
Very smooth, and quicker than expected.
by Grouchy-Zucchini-984