I bought this at a vegetarian shop in Kyoto (~15 minute-walk from Kyoto station).
I discovered this just recently because my husband tasted a takikomi gohan cooked by a friend who used this very product. My husband really loved that takikomi gohan so he bought this seasoning (which happens to be the smallest pack, 500g for ~￥750.oo) and kept on bugging me to replicate that dish. I'm not sure if I perfectly replicated it because the recipe I got from my friend didn't have any measurement (like most of my recipes here ^^;) but my husband loved it so much.
If you want to buy this or browse over other vegetarian products they sell at that store, you can check out the blog I wrote about them.