魔法騎士ピュアナイツ ～巨根には勝てなかったの オトメの穴捧げます♪正義のヒロインは孕ませハーレム肉便器♪～

The main character is a middle-aged man with a big dick and sexual desire.
He has a huge cock, but he has no use for it and spends his time in vain.
However, he is saved by the heroine of justice, the magic knight Pure Knights, who tells him that the life energy generated by his powerful, manly cock will make them stronger and asks him to cooperate with them.
The hero willingly agrees to help, and then he takes all of the frustrations and sexual desires that have built up over the course of his life and fucks the Pure Knights, who are all beautiful girls, as pawns!