THE ROYAL TUTOR MOVIE

The four princes of the Kingdom of Granzreich are aiming to become the next king. Under the guidance of the royal tutor Heine Wittgenstein, while overcoming various obstacles and sometimes hesitating, they grow little by little. Appearing before them are twin princes from the Kingdom of Romano. Even though these princes look cute on the surface, they are actually extremely sadistic...! Towards such an unprecedented crisis, Heine and the four princes perform "educational guidance"!? (Source: Official Site) — Description from AniList community (anilist.co).