1. A head-mounted display device comprising: a camera; a see-through display configured to display virtual imagery, and capable of transmitting external light through the see-through display; and a processor or circuit configured to: control the camera to continuously acquire images, and while the camera is continuously acquiring images: detect, by image processing, whether or not the acquired images include image data that is the same as image data of an operation object stored in a memory; and if the acquired images include image data that is the same as the image data of the stored operation object: control the see-through display to display a virtual image associated with the operation object; detect, by image processing, a gesture associated with the operation object; and when the gesture associated with the operation object has been detected, control the see-through display to display a specific check image associated with the operation object.