Ayakashi Sange by Debo no Su Seisakusho - Adult Sex Game

The demon world was united by the rare mastermind Ibaraki Shouhou. However, he was assassinated by his chief vassal Sarugami Gensuke before he could attain his dream of conquering the human world. With the loss of its absolute ruler, the demon world fell into a state of chaos and strife. Shouhou’s son Jinkurou decided to seek revenge for his late father and attempted to rally the surviving retainers for his cause. However, he had been disinherited and ousted for being a womanizer, so no one answered to his appeal. Thus, he set out with his most trusted friend Iori and loyal retainer Kuroko to re-unite the demon world once more.