Traditionally it is served in Fukuoka, but you can find it in other areas too. Photographed here is a small tonkotsu restaurant from Namba, Osaka, with a typical Japanese atmosphere...
EXIF info:
Nikon Df
Lens: 24-70mm F/2.8G
Focal Length: 24mm
Aperture: F/4.5
Shutter Speed: 1/60s
ISO Sensitivity: ISO 4000