Kanata Tono finds a strange box in the house of his childhood friend Mana. Inside the box, there are actual people living, and upon closer inspection, it seems to be a world from medieval Japan. Curious, he continues to observe, but one day he sees a girl being attacked by a thief inside the box, and unintentionally kills the thief. Upset, Kanata goes to her house to talk to Mana. However, Mana's father tells him an unexpected truth. "But Mana's father tells him an unexpected truth: "We don't have a daughter named Mana.