Once upon a time, Nana and Elly went to see a Seiko artist's concert, and they couldn't find a seat. Incidentally, there were still two empty seats in the front row, seeing that no one had occupied them, they immediately took them. But they were expelled by the event committee, he said the seats had been reserved for someone. Nana didn't want to leave the place, the atmosphere was getting hotter because the two of them didn't want to budge. Who will occupy the seat?