A boy and his Arnval Shinki, nicknamed Ann, move to his hometown in Japan to start high school. As Ann helps unpack her master's things whilst he is at school, his other Shinki, Ines and Lene, help her out and discover a box labelled 'Important'. After tidying up the place, they inadvertently send a knife flying into the 'Important' box and decide to check the contents, finding a love letter inside...