We are developing a VR mirror therapy system that is portable and can be operated with the user’s own hands. In this system, the user grasps the rolling balls on a slope-toy-like task stage in VR space with virtual hands, and returns the balls to the top slope. To achieve natural grasping of the ball with the healthy limb, fingertip positions obtained from XR Hands were used. Users are expected to wear a prosthetic hand on the affected limb. The system recognizes the affected limb as a hand, and the user can grasp the ball with the affected limb by clicking the button of the wireless mouse attached to the healthy limb while the virtual hand is displayed. In this paper, we introduce the features of the system that enhance the usability and effectiveness of the treatment. We also describe experiments to verify the operability of the ring mouse and the effectiveness of the ball color change when grasping the ball.