This case is initially a 40 square meters living space with one side 60cm lower. This small space is divided into two by the difference of height. Thus, the designer tries to make a good use of the situation, arranging two storeys on the sunken side, creating a comfortable living space customized for an owner and a cat. A wavy flow meandering as the axis of the space prevents lines from forming too many corners. Not influencing the public space’s comfortness, the designer maximizes the smoothness of the flow and size of the storage rooms, creating a sense of security of the owner's wish.