A Letter to Momo

Following the death of her father, who left her a letter that never got beyond a greeting, Momo struggles to come to terms with her grief and guilt, and finds herself distanced from her mother. When the two move to a new home on a remote island in the Japanese Inland Sea, Momo befriends a young boy and his perceptive younger sister, a timid postman and three rascally goblins. With their help Momo prepares to take the plunge into her new life on the island.

Synopsis from Anime News Network