Switching gears for a moment to document some soba I made off the top of my head. I'll try to keep the words to a minimum and let the pictures talk (zoom into the picture for recipe type shits).
Chris and I had cold soba while in Sendai this year, though I'm pretty sure the broth was nothing like this. To be honest, I haven't yet bothered to look up a recipe, but this sauce has worked pretty universally with various Japanese types of cuisine.
Authentic? Probably not.