The answer is depends on each clinic. However, I recommend you to make an appointment for a Shiatsu treatment in advance. One Shiatsu session takes 30 minutes at least, so it often takes you a long time to wait for your turn without making an appointment. Especially in the evening, most of Shiatsu clinics are crowded with patients who are on their ways back home from their works, therefore you had better ask the situation on the phone and visit the clinic for a Shiatsu session after making a reservation. In our clinic, for example, we ask all of our patients to make an appointment on the phone or by e-mail before their coming.