Alright so I read the first five episodes and I must say...
It seems very interesting so far. I like how in the opening describes the setting's backstory. No overly long dialogue or waiting 30 episodes for it to be explained. From the dialogue, even in the first episode, we can tell Vivia's personality from the interactions alone. When she dies it comes out of nowhere... which is good, that's the point!!!
I love the descriptions fo what she goes through when she dies, it puts us in her position to imagine the pain and feeling. It's funny how she thinks he's a grim reaper saying "I didn't know they sent such handsome grim reapers" and "Maybe they show one last pity". It ends with a reveal that leaves you wondering what comes next. The story then explains what happened and how she "reincarnated" into a murdered princess. (Although it seems more like she simply took the princess' place once they both died.)
The sword scene showing VIvia/Princess Clairette isn't just a helpless victim was cool, another moment to establish the character's personality. Later we see the Realm of Harmony, which description I really liked. It captures an etherial or even dream-like feeling that feels oddly cozy, yet mysterious. It's great we get a valid reason for why Vivia just rides with this "demon" guy she just met. The whole death of the Princess makes one curious for the whole context. Why is Vivia in the Princess' body now? Who killed the Princess? Who killed VIvia and why? How did the people watching the spectacle react?
However, the fact that the text calls Zerath by his name before it's revealed in dialogue is weird. It works better if a character is unnamed by the narration until after the name is revealed in dialogue.
This world is familiar with the terms "Yin" and "Yang" which is interesting...
Also, it's oddly surprising too how neither are prejudiced against each other's kind... I can understand him not being prejudiced, but her too? But I like their interactions, there's already some chemistry between them.
Overall a solid story that really makes you want to know more. Good job!!!!