I'm back in Japan for the eighth time, but it's five years since I was here and some things are changing.
I've found that every Lawson convenience store now offers free Wi-Fi in one-hour sessions that you can use a certain number of times per day (I think 5 times, but I'll check).
Obviously every accommodation from the level of backpacker hostel up has free Wi-Fi. (Rider Houses often do not.) I'm sure it's common in restaurants and cafes too.
So far the only other place I found free Wi-Fi was at a Michi-no-Eki (road station) in Chitose, Hokkaido. Maybe all Michi-no-Ekis have it. I'll find out and report back.
What I'm looking for is, when you're out and about and suddenly need Wi-Fi to contact a friend or book a hostel, where to head where you know you'll get it?
Many times in many countries I've paid for a coffee I didn't really want, expecting Wi-Fi, and found it wasn't offered, cost extra, or required a local phone to register, etc. In Japan I can just head to the nearest Lawson, but are there other possibilities?
This question is not asking about cheap or convenient Wi-Fi or data plans. There are many such available all around Japan. Please don't answer "just buy this or that card or plan, etc".