We went to this Japanese restaurant the other day, and it was great. I thought I'd never see sushi again when I moved to Riyadh, but I was dead wrong. They offer all the main dishes that you would expect of a japanese restaurant, but of course with their own spin. Not all the dishes will taste authentic (.e.g noodles), but many of them come close and are still tasty in their own way. They have fresh sashimi, and they do a really good tempura. It's also priced reasonably in comparison to places like Shogun.
Tokyo used to be a teppanyaki place, but they said they closed down that service because of complaints about the smells (!??!). Do not get too excited if you see a teppanyaki table - that knife show is not gonna happen for you. The family section is entirely sectioned into booths. I'm not sure about the singles section, but in general it's definitely not the fanciest looking restaurant in Riyadh. Like Diamond, it also has mirrors plastered all over the ceiling for some unknown, unholy reason.
My raving review must unfortunately come with one strong caveat. Tokyo is inconsistent. If you happen to be there on a day when their fish arrive, you will be extremely happy with your sashimi. If you happen to be there on a day where their stock is a few days old, you will taste it. So like shooting a dart blindfolded, but still worth a go if you're really missing your sushi.