In this study, we investigate the capability of ultrasound to present softness and hardness sensations through physically limited stimuli, thereby extending mapping to the stiffness properties of objects in the real world. By applying spatiotemporal modulation in mid-air ultrasound tactile displays, we alter the radius of the focus trajectory based on a finger’s vertical movement. Thus, the contact process with objects of different compliance is presented by varying the contact area. In addition to the radius change, we set a series of speed levels to alter the perceived intensity during pressing. Through psychophysical experiments, we investigate the rendering realism and softness perception of the presented rendering method. Stimuli with a low focus speed and a large rate of change of contact area during pressing are perceived as softer. Moreover, we achieve a 4.5-fold softness range between the softest and hardest stimuli while maintaining a certain level of rendering realism.