Aoi Blink

Summary:

The story opens with the meeting between our hero, Kakeru, and a mystical pony named Blink. Kakeru saves Blink from a thunder shower and in gratitude, Blink tells him that if he is ever in trouble, all Kakeru needs to do is call out his name and he will appear. At the end of the summer when Kakeru returns home, his father, a writer of children's stories, is kidnapped. Kakeru, weeping, calls out Blink's name and, as promised, Blink immediately appears, and the two set out on the trail of Kakeru's father. Only at the end, when Kakeru woke up from his deep sleep found out that all his adventures with Blink was only his father’s writings that shown in his dreams.

Wikipedia