If there are openings available, then it is possible to jump by simply showing up at our office on the day.  Customers with bookings will be given priority however, so it is possible that you might be subject to a long wait.  Weekends, national holidays and holiday periods such as Golden Week, O-bon and summer holidays can fill up quickly so booking well in advance is strongly recommended.  At all times however, making a booking is recommended to avoid disappointment.