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. When the wind suddenly blows the letter away, the Shinki chase after it as it knocks over another Shinki named Kurara, who takes it as a challenge and forces them into a battlefield. When the letter becomes slightly damaged as a result of the battle, Ann becomes angry and overhwelms Kurara in battle before heading back home. After their master returns from school, Ann apologises for what happened to the letter, which is revealed to contain a visualizer containing a house he made for Ann when he was little. Later, they discover another box containing a Strarf model Shinki.