We propose a glass-free aerial interface that forms aerial images from real objects of various shapes. The proposed optical system can be increased in size by simply increasing the size of each of its optical components. It forms a high-sharpness aerial image by approximating a real object with a spherical shape to a lens and placing it at the focal length. Combined with a motion sensor, it can be used as a non-contact user interface. The proposed optical system can be a new aerial display design that matches the real space by changing the shape of the real objects.