Comparing with photos in a Google search, I believe this is a sushi dish made from squid. But I am not entirely sure since its been more than 11 years since I had this dish in Tokyo and I am not into Japanese food or sushi. Normally you will have some sort of rice filling under the fish but this seems like a solid piece of white tender meat coated with a yellow sauce sprinkled with some white sesame seeds. If you have a better idea, please write to me so that I can do justice to the naming of this Japanese dish. Thank you mates.