An image processing system according to an embodiment includes an input unit, an output unit, an acquiring unit, and a display unit. The input unit receives setting of a landmark in first medical image data obtained by capturing a certain tissue of a subject. The output unit outputs data including information of the position of the landmark in the first medical image data as output data. The acquiring unit receives the output data and acquires, based on one or a plurality of pieces of second medical image data obtained by capturing the certain tissue of the subject and the position of the landmark, three-dimensional position information of the landmark in a three-dimensional capturing space of the second medical image data. The display unit displays image data obtained by superimposing the first medical image data on the second medical image data, based on the three-dimensional position information.
