While I don't know about this specific case, it wouldn't necessarily be surprising to see 'fusion' food exported. You can get chicken tikka masala, which is a British Indian invention, all over the place these days (and in fact even the katsu curry might be a remote descendant of British Indian 'fusion' food; AIUI the Japanese navy adopted curry from the British in the 19th century).
The name of the dish is simply kare rasiu (curry with rise) and that's most common form. It's also super simple to make if you have rice cooker at home. Just pre-fry some onion, carrot and potatoes on the pan, then boil it with considerate amount of water and add curry blocks to it - done. You may add meat but it's just an additional ingredient which can be easily omitted. You can make it once and it lasts for couple of days. You can even freeze it if you want.
We have 'wagamama' which at best can be said to be japanese influenced, and a few chain sushi places (like Yo Sushi) across the country. They really aren't all that great. But if you look at some of the smaller/independent Japanese places that are around and about, they seem to be far better quality. I think London probably suffers from its centre being dominated by chains.
But on katsu ... I've had Chicken Katsu Curry in the UK, sure, but also in Australia, in Singapore and in Bangkok. If that's not a big thing in Japanese Cuisine then quite a lot of the world might have grasped the wrong end of the stick!