Natsu e no Tobira is an anime film that premiered in spring 1981, produced by MADHOUSE.

About the production: the story comes from a manga, the film runs about 59 minutes and its current status is "finished".

Its main genres are drama and romance, with themes such as Coming of Age, Age Gap, Shoujo and Male Protagonist.

On AniList, Natsu e no Tobira has an average score of 58%, an average score, and appears on 3,204 users' lists.

Marion is a young schoolboy who prides himself on his adherence to a philosophy he calls "rationalism". Because of his disdain for emotional display, he ignores anything remotely akin to affection. But when he's entangled in a romantic affair with an older courtesan, his rationalism is revealed to be little more than a cover for his own emotional immaturity. Learning to love, Marion blossoms under his older lover's care but unfortunately, Marion has yet to learn the true price of the affair. (Source: Anime News Network)

Official synopsis from AniList.