Almost everything else in Kanazawa is walk-in: the garden, the market, the castle grounds and the tea districts all work without a reservation. Myoryuji is the exception, and it is the one thing here that can quietly fail if you leave it to the day.
The friction is not the lead time but the channel. A telephone-only system in Japanese business hours is a real obstacle from abroad, and it is worth solving before you arrive rather than from a station platform.



