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