A shoulder bag of a size that fits A4 documents, not too small, with a simple and essential design. By eliminating the lining, a moderate softness and a casual feel are achieved, without being too formal. The shoulder belt can be attached and detached with a buckle. In addition to an inner pocket with a zipper, there are also small zippered pockets on both sides of the main body, perfect for storing small items such as smartphones and wireless earphones.