Kimi no Mana wa Rina Witch

At Witch School, students are taught that supplying mana, which is derived from sperm, is considered a holy duty. To maintain a consistent source, each girl is paired with a boy. Sexual activity is neither purely recreational nor aggressive; it is a necessary practice. The mana produced amplifies a Witch's abilities, enabling her to fight against creatures known as Eaters. Mastery of various sexual techniques is therefore encouraged for all, as greater pleasure yields higher-quality mana, resulting in a more powerful Witch.