Portable terminal device, displaying system, and method of controlling display on portable terminal device

A displaying system, comprising:

• a display device including a display screen having an aspect ratio determined between a length and a width different from each other;
• and
• a portable terminal device, including a terminal display screen having an aspect ratio determined between a length and a width different from each other;
• an accepting section configured to accept instructions of change to change a display condition of the terminal display screen;
• and a display controller configured to change the display condition of the terminal display screen from a first display condition of displaying a first image to a second display condition in response to acceptance of the instructions of change by the accepting section, the second display condition being such that the first image displayed in the second display condition is reduced in size when compared with that of the first display condition, and that a second image not displayed in the first display condition is displayed in an empty region formed by reducing the size of the first image.