Yup. When I used to travel to Japan for work, Japanese colleagues took us to a restaurant specializing in tonkatsu. One of the best meals I had over there. Each person got a mortar and pestle to freshly grind sesame seeds to add to the tonkatsu sauceKatsu means cutlet, tonkatsu for eg is pork cutlet. Loads of places now called the curry sauce 'katsu sauce' when it's not. The sauce for the pork cutlet is more of a brown sauce type thing
I have read somewhere that Japanese curry sauce was invented during the war when British soldiers brought over curry powder as there wasn't a 'curry' in Japan at the time, which kind of would tie into what you heard too










