Each item is capable of moving back to a specified location after being moved, similar to how Nissan's ProPilot Park system is capable of using the steering, brakes and throttle to maneuver a vehicle into a parking space without human input. That means everything at the ryokan is always in the correct spot, and I imagine anyone staying there would get a kick out of watching slippers and tables move about without help.
This isn't the first time Nissan has added some of its tech to ordinary objects. Last year, Nissan built an autonomous chair to alleviate the strain of queueing -- when a person gets up from a chair at the front of the line, that chair moves itself to the back of the queue so another person can sit down and wait for... whatever's at the end of the line. Whether it's waiting in line, arranging slippers or parallel parking, ProPilot is all about reducing tedium.
According to Cnet