To beginn: it is not Princess Resurrection

I don't have a lot of inormations, but i hope it is enough: It is about a guy with a sick sister. He get accidently killed by a girl and she resurrected him. He doesn't want to believe that is true, but the sickness of his sister gets worse because of him. Also he need to drink her blood every few days or he dies.

She is from another world and he is forced to go with her, also to not make it worse for his sister.

I don't know a lot of the storyline, since i began to read the sequel first (but i also didn't read the sequel completely, so i also don't know the title)

In the end of the prequel the sister get abducted, and he goes nut what we see in the sequel he is a tyrannical ruler. This change in the manga later. Also he is in love with the girl above.

I hope someone can help me to find it.

This is it, thank you!