Ryu-chan is very blessed to have you as his Shiba parents. He's thriving because of your love and tender care. Even though he's a dog, I understand the difficulties of gastrointestinal problems because I have them and can relate to them when things get messy and painful. You are correct in saying that dog food with grain is more challenging to find because most of the gut problems are down to grains in dog food (something to do with digesting the type of grain). Unfortunately, UK dog food brands might not be available in Japan (although I've seen Royal Canin on the shelves of my local shops). Small business dog food subscription companies in the UK can assess your dog's needs and tailor the food to your dog's nutritional needs (after a visit to the vet to monitor weight and rule out other issues). The thing with Ryu-chan - stating the obvious, I know - his nutritional circumstances are unique, and you are incredibly careful about what you give him because he didn't have a good start in life before you welcomed him into your lives and almost died. He loves his food, though, and he loves you all. He's in my prayers. A Shiba Inu puppy (a few months younger than Ruy-chan) is on grain-free food because her Shiba Inu mother developed allergies and had to be put on a vet prescription. Ever since my Shiba pup came home with me, I've been monitoring her food and poop very carefully. I wish you Peace and All Good for the New Year.