Hero - My semen from the landlord's capital is my target

There was a world where people and monster girls once fought and began to walk the path of coexistence with the exploits of heroes. 100 years later... A horde of unknown enemies and weapon girls invade from another world. Humanity and monster girls are forced to be at a disadvantage in the face of overwhelming amounts and strength. In order to protect the village, the protagonist takes courage and challenges the weapon girl to a fight, but loses easily... Just as she was about to be raped, she was saved by a monster girl. His name is Lizesnare. He was the demon king who once ruled the world. The protagonist thinks "I'm saved..." but for a moment, the demon king gives him a footjob and squeezes out her semen. Despite suffering such a terrible situation, he suggests that he fight together in order to defeat the weapon girl. The Demon King, who has yet to regain the power he had been 100 years ago, has set conditions. "I will regularly exploit your semen from you. If you can afford these conditions, let's fight together." The protagonist is troubled, but he accepts it... This is how the heroic tale continues to be targeted by both the protagonist's enemies and allies, and begins.