Quite surprised that one of my local supermarkets has mirin as well as rice vinegar, also a few other bits and pieces such as miso stock, dashi, wasabi paste, and of course udon noodles. We don’t have a Japanese community or dedicated East Asian groceries where I am, so there isn’t much demand I expect (in London they will have more through). Perhaps one day I will be brave and actually cook a proper recipe like tonkatsu - that was Sunohara’s staple convenience diet wasn’t it? You’d have to be still braver to try my cooking!.
I’ve been drinking green tea for a few years but only just tried sencha and matcha - can’t tell any difference in the taste between them but they are both much more refined than the “standard” green tea.
And also surprised the other supermarket has just started selling Chicken Chilli Ramen - just ready meal for microwave, as well as Firecracker chicken/prawns, gyoza, plus the range of “bento” sushi and katsu.