Rumi Yokoi only wants to concentrate at school, but she is continually distracted by Toshinari Seki, a classmate across the hall. Seki isn't concerned about paying attention in class since he is preoccupied with sophisticated settings made from a variety of materials, ranging from an extensive domino course on his desk to a treacherous battle fought with shogi pieces. Yokoi tries valiantly to concentrate in class, only to get caught into his fascinating idiosyncrasies, which usually seem to result in her getting in trouble with their instructor. Fortunately, with Seki's shenanigans on the scene, lessons will never be boring!