Tokimeki Tonight: Hoshi no Yukue

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...