This paper describes the development of a new shank mechanism and mimicking the human-like walking in the horizontal and frontal plane. One of human walking characteristics is that the COM (Center Of Mass) motion in the lateral direction is as small as 30 mm. We assume that it is thanks to the human walking characteristics in the horizontal plane that the step width is as narrow as 90 mm and the foot rotation angle is 12 deg. To mimic these characteristics, we developed a new shank and implemented it in a humanoid robot WABIAN-2RIII. It has a parallel mechanism which mimics the shank's size of human. Thanks to its size almost the same as human's the robot is capable of realizing gait with the narrow step width of 90 mm and the foot rotation angle of 12 deg. We evaluated the performance of the shank using WABIAN-2RIII. The robot could realize stepping in place with lateral displacement of CoM within 34 mm, which is almost as small as that of human.