*SPOILERS AHEAD* This book follows the story of a man in the modern era who inherits a system from a goddess that grants access to levels and stats and turns him into a vampire girl. The main character (now named Eira) proceeds to prepare for the return of the cosmic mana stream, which is the original source of stats (separate from the goddess's system). This book also receives regular updates three times a week. I will warn you that there are some dark and potentially disturbing scenes, but nothing too bad, and it adds a realism to the story that many other books don't have.
Eira is a vampire who is not adverse to killing to get what she wants and/or needs. Great personality and good background. Although she was a man before, she now fully identifies as a girl. One thing to note is that she is constantly getting more powerful, and is much stronger than a regular human. Some could argue that she is evil, others would argue that she is neither good nor evil.
There are a number of side characters in this book, some of which do die. Overall, Eira's companions are well developed, especially Eden, who has a well-developed background. The author isn't afraid to kill certain characters, but that doesn't mean important characters are dying all the time, likely due to Eira's strength.
If you like a clearly laid out plot, where the character clearly know their enemy and has to stop them, this might not be for you. The main antagonist (or who I think the main antagonist is) has not been developed, however, the book is likely still in its early stages. I use the word antagonist as an enemy of the mc, not an evil person (although they could be) because Eira isn't exactly "good," but nor is she truly "evil." Back to the plot, this is similar to a survival-apocalypse story, but not quite. Instead of just "survive" Eira has a clear goal in mind, however complicated it may be to get there. Overall, a good plot.
The story takes place on earth, with a few changes. First of all, an extremely small amount of people have strange abilities, however this is not common knowledge. There also exists other dimensions and other races, however pureblooded members of these races are not found on earth (at least not at the start). Since the book is first-person, we learn about other races and such at the same pace Eira does (with some exceptions).
The writing of this story is good, with well chosen words and a flowing narrative. We can see all of Eira's thoughts, as it's first-person, but the point-of-view also changes to other characters (also in first-person), allowing us to see Eira and the world from other perspectives. The PoV changes are really nice to see and fit well in the writing. The only problems are some minor grammar mistakes that are scattered throughout the book, but they don't break the immersion, and everything else more than makes up for it (most of them get fixed anyway).
Overall, this is a really good book and is definitely worth a read. If you like the gender change part, good for you, if you don't, it doesn't have too big of an impact on the plot so you don't have to worry.