The Ground Detective is back! In this episode, he travels to Kagawa Prefecture on Shikoku Island. People come here from all around to enjoy its many udon noodle shops, numbering over 500. What is it about the local area that gives the udon noodles here their distinctive firm but sticky texture? Is it the fact that Kagawa faces an inland sea? Is it in the history of farming here? Is it related to earthquakes? The pieces of the puzzle are salt, flour and water, the only 3 ingredients for these noodles. And the Ground Detective is on the case!