A medical system includes a medical device, an over-tube, and a console. The medical device includes an insertion portion. The over-tube is configured to receive the insertion portion. A console having a first connector is attached to the medical device and a second connector is attached to the over-tube. The over-tube has a tubular main body and a proximal-end portion. The proximal-end portion comprises a tubular member having an insertion port for receiving the insertion portion of the medical device therethrough. A base portion is coupled to the second connector and a moving mechanism is coupled to both the tubular member and the base portion. The moving mechanism is configured to cause the tubular member to move with respect to the second connector such that the tubular member has two or more degrees of freedom with respect to the second connector.