The first its good but its not the manga im searching, the demon first is male and then get genderswap, and there be a demon girl making the hero gender swap, like the second link but in this the demon is a man and not a female . The contents are these:

1-Demon girl use magic or item
2-Hero male get genderswap
3-Demon gir fuck hero, i don remember if the demon gir become futa or it was a yuri
But i remember in the last panel was the demon girl watching the hero being fucked from a cristal ball