(i) a memory configured to store computer-executable instructions and a processor configured to execute the computer-executable instructions stored in the memory, (ii) an integrated circuit, or both (i) and (ii) that cause the information processing device to:

acquire information on a line drawn by a user with respect to image data in which the predetermined place is imaged; and

determine a range indicated by an area on the line as the monitoring target range, a thickness of the line being increased, wherein

(i) the memory configured to store computer-executable instructions and the processor configured to execute the computer-executable instructions stored in the memory, (ii) the integrated circuit, or both (i) and (ii) cause the information processing device to:

calculate thicknesses of the line at locations of points of the line in a case where the thicknesses of the line at the locations of the points of the line are increased until the line reaches a boundary location included in the image data; and

determine a range indicated by an area on the line as the monitoring target range, a thickness of the line being increased by a length of a representative value of thicknesses calculated at locations of a plurality of points among the points of the line.