A guide will be waiting for you right outside of the ticket gate in front of the station at the time of your train arrival. There is only one ticket gate for Yamato-Kamiichi Station, and if there is somehow a mix up, the Information Center is about a 30 second walk to the west (left).
On the same train line and only 2 stations away from the starting point of the tour (Yamato-Kamiichi Station).