This paper aims (i) to introduce a new monolithic micromanipulation system for applications requiring micro / nano scale planar motion, and (ii) to model its stiffness consisting of the inherent stiffness of its joints, and the artificial stiffness due to its joint space position controller in order to obtain a decoupled compliant motion for the manipulator end point while a Cartesian force vector is acting upon it. The micromanipulation system is an in-parallel actuated planar manipulator based on five single DOF flexure joints connecting five supposedly rigid links to each other. Numerical results provided show that there exist practical operation ranges of the manipulator yielding both a suitable set of joint servo gains as well as a diagonal Cartesian stiffness matrix. The stiffness model can be used to predict the reaction forces arising from part misalignment and the task forces during the execution of micro tasks, such as micromanufacturing and microassembly. The determination of the forces is also useful for many applications such as designing micro fixtures and micro end effectors sustainable to task forces.