What was the first Hentai ever made? I just want to ask what is the first Hentai manga and what is the first Hentai anime?
The history of Japanese hentai manga is very, very old.

For example, The Dream of the Fisherman's Wife (NSFW) was drawn in 1814.
The work is also known as the earliest tentacle erotica.
In 1722, the government created a law to ban hentai manga.
This means hentai manga had already been known in public.

For Japanese hentai anime, Wikipedia entry says Suzumi-fune (1932) is oldest hentai anime.
But well-known oldest hentai anime is the Cream Lemon series.
This series was ranked in the best-seller video list (which contains non-adult videos.)