Mahou Shoujo wa Kiss Shite Kawaru / 魔法少女はキスして変身[かわ]る

After Iori fell in love with Ken at a young age she wanted to be his wife more than anything. Ken feels the same way about Iori. When Ken is nearly killed by a monster she is told the only way to save him is to have sex with other men to make her more powerful as a magical girl....