Zenryaku, Hatsukoi no Kanojo ga Ikikaerimashita.

A man living in Tokyo, distant from his hometown, has been trying to move on from the death of a friend he once had unrequited feelings for. After years of solitude, she unexpectedly appears, looking exactly as she did at 18, despite having clearly died years earlier. He is stunned, unable to understand how she has returned. Neither of them knows why she has come back unchanged, as if time had not passed for her.