I Possessed the Northern Grand Duke, and It Appeared?

*This work contains elements such as intersex (hermaphroditism), womb-related tropes, and multiple male leads (polyandry). Please keep this in mind before reading. One day, Sayun wakes up as 'Iliya,' the Northern Grand Duke in a fantasy game he frequently played. While he is still completely disoriented, a system window gives him a quest to resolve the Demon King's curse. Told that he will face a penalty if he fails, he tries his best, but ultimately fails—triggering the curse of 'Asmode,' the Demon King of Lust and Pleasure. As a result, his body undergoes changes, and the curse (estrus) strikes him at the most inconvenient times... To break the curse and return to his original world, Sa...