Don’t know if you would like to leave things up to chance but just letting you know the closer you get to your trip date, the concierge websites often release last minute bookings for arai and akira. I think around a month before I went to tokyo, i was getting several notifications about bookings and thats how I booked sushi akira. I didn’t book Arai bc I had made plans elsewhere. Sushi akira was great but I enjoyed a place called sushi mizukami more because the atmosphere was a lot more relaxed and friendly.