Aira is a 16-year-old witch trainee who has a dashing boyfriend, Shinjo. One day he tells her about his unknown past; he doesn't have any memories of his childhood. Curious, she travels into the past through her family's secret time-doors and found out that he is actually her childhood friend, Kairi! She's upset when she came back to the present and saw Shinjo turning to Kairi. He has no recollections of being 'Shinjo,' but he still remembers his childhood days with Aira. What will Aira do?

Meanwhile, an evil comet from space is approaching. Will Aira continue to lament the 'loss' of her boyfriend or will both of them fight together to save the world?