Pure Pure Pero Pero Princess OVA

A single, 42-year-old man is unexpectedly summoned to another world by a princess named Alice. She explains that her kingdom is facing an apocalyptic disaster and that the only way to save it is by mastering sexual techniques to power a mysterious formation called the “Death Gate.” The man becomes her instructor in this endeavor, and their explicit “lessons” are discovered by the Queen, who initially disapproves before the man attempts to justify his actions as necessary training.