https://www.gally.net/temp/20260518-japan-transmission-grid/...

The image produced by the program seemed unbalanced because Japan’s southernmost islands were included even though they are not part of the electrical grid. I used an image editing program to remove the outlines of those islands and shift the main part of the country toward the center.

Side comments:

Not indicated on the map is the fact that Japan’s electrical grid runs at 50 Hz in the eastern and northern parts of the country and 60 Hz in the west:

https://en.wikipedia.org/wiki/Electricity_sector_in_Japan

The electrical power distribution system is now undergoing a major redesign:

https://souhai-sys.co.jp/business/ (Japanese only)

I was thinking of printing one that's like the California example (https://github.com/open-energy-transition/grid2poster/blob/m...). Where do people print posters nowadays?

For north america also look at this https://geovizzydesigns.myportfolio.com/electricity-grid-of-... , more complete only in the US since not rely on OSM

https://openinframap.org/