Shimada was raised in a snow-suffering village in Yamagata. Elderly locals taught him how to play shougi and when he became a middle school student, Kai started going to the Association in Tokyo twice a month while working part-time to pay for related expenses. He continued playing shougi even when he seemed to be getting nowhere and despite stress-related stomach pain. He would look on as the same-aged Souya ran in and out of the Association, racking up one title championship after another. Shimada could see that he wasn't closing any distance between himself and Souya, but couldn't afford to slack off. In the present, Rei accompanies Shimada to Kyoto, site of the fourth match of the Lion King Tournament.