I have never been but I did some research. It seems like an old school premium teppanyaki restaurant...
If your budget is over 35,000 yen per person and you are willing to pay that much, I would personally recommend going to another restaurant that grills its steaks in a kiln type oven.
I agree, there is no balance and finding that optimization is difficult. It does not help that a lot of famous Instagrammers have already curried favor with restaurant owners and are already regulars/VIP and trusted status, and by posting they attract so much envy and copycats.
I suppose the idea of implementing online reservations requiring a credit card hold/deposit with x1.5 or x2 cancellation fee is still a while away. But we don't want them to sell prepaid tickets entirely either, that is a terrible business model where the cost of the ticket (and reservation system) is passed on to the customer.
Out of several new sushi restaurants that have sprung up, I have carefully selected seven that are particularly noteworthy to feature here. Go ahead and book a table to dine at one while reservations are still easy to get!
Where possible, I think it is better to make a reservation in advance of your visit. However, as we do not accept reservations for Sushi Ishijima, please expect some waiting time on the day of your visit.
My hotel concierge was able to reach them. Not sure whether it's helpful, I am using park hotel tokyo. And probably good to get your hotel concierge to start calling them once they open reservations 3 months ahead.
Apparently, the ¥4,800 course will be discontinued by the end of May. The ¥12,000 course will be available "with otsumami" or "with nigiri only." The nigiri only course will include 12 pieces of sushi. It seems it will also include expensive ingredients like chutoro, otoro, sea urchin, etc. The ¥4,800 course was such an abnormally good deal that the ¥12,000 course seems rather expensive in comparison...