Continuum mechanisms have drawn wide attention to scholars due to their salient advantages including compliance and dexterity. In this paper, a planar continuum mechanism made of soft panels is proposed. This mechanism has a reduced degree-of-freedom (DOF) compared with some existing continuum mechanisms capable of 3D motion. However, it can meet some application requirements in the field of robot and aerospace due to its characteristics of small stiffness in the motion plane and large stiffness perpendicular to the motion plane. Besides, a combined kinematics and statics modeling approach is presented for this mechanism by using the classical beam theory and a constrained optimization method. In order to ensure the model accuracy, a hybrid approach is proposed to consider gravity depending on the deformation under study. By comparing our results with those from the commonly used constant-curvature method, it is shown that our model is more accurate in predicting the deformation shapes.