Despite its high lesion accessibility and versatility, endoscopic platforms have suffered from designing flexible manipulators with high payload capability sufficient to perform advanced endoscopic procedures. A flexible robotic platform, K-FLEX, has been developed with a design of 17 mm in overall diameter. To overcome the shape distortion and deflection in payload handling, a strong continuum manipulator has been designed to have maximum resistance to the distortion. The kinematic analysis and mapping strategy have been established for the master-slave teleoperation. The proposed manipulator has shown 7.5 mm in trajectory variation to lift the weight of 300 g. Finally, the feasibility of the integrated K-FLEX system has been verified through three kinds of simulated surgical tasks. The initial prototype of the proposed robot showed the possibility of advanced endoscopic surgery with improved payload capability.