Big book small book

and she shoulda died
that way my girl vaporeon will show up and whoop Muzan Kibutsuji's ass

Can we kill Mitsuri as well?

One: I don't want Mitsuri to die.
Two: She already dies in the manga.

The incarnation of water breathing: Vaporeon.

True but it depends. Does Giyu make him a demon slayer still, or does Tanjiro just go on with life. If he becomes a slayer than he may still go after Muzan. Maybe and maybe not. Depends.

As a DS fan I can confirm your statement is true