Kimi no Mana wa Rina Witch, Episode 1 English Subbed

君の魔名はリナ・ウィッチ / Kimi no Mana wa Rina Witch

“Taboo Zones,” enigmatic spaces that suddenly appeared all around the world. Within them manifested the monstrous “Eaters,” creatures that consumed human spirits. Humanity was helpless against the Eaters, impervious even to physical and nuclear attacks…
However, humanity was not powerless forever. They discovered a way to fight back using a technique called “magic,” harnessing the life energy known as “Mana.” This magic was the only means to defeat the Eaters. Warriors capable of wielding magic through Mana were referred to as “Witches.”
To nurture these Witches and their partners known as “Familiars,” Witch Schools were established. The protagonist, Shunya Iizuka, initially failed the entrance exam, but due to his exceptional stamina and ability, he was invited to enroll.
In this world, non-magic-wielding men are sought after for a specific purpose: to supply the Mana that serves as the source of a Witch’s magic. Through a process, their bodily “Mana = sperm” is converted into Mana, making them unable to use magic themselves. Instead, they can replenish Mana semi-permanently by providing their sperm to Witches through sexual activity.
And so, Shunya’s life at the Witch School begins…”