@SlyHand I finished reading what you have so far. The grammar is good, so I had an easy time following the story. Just make sure to proofread your novel at least twice, since there were a lot of places where you forgot punctuation, especially after dialogue. Another thing I wanted to mention is the prose. Try not to use "very" too much, since it's a dead word (one of my college professors used that term to describe those types of words). Essentially, "very" is often an unnecessary adverb/adjective that can be cut out without changing the sentence too much.
Now, on to my critique of your story:
The prologue was intriguing, and it did a good job of setting up the world. By writing it in a diary format, you managed to deliver exposition while tying it to a character's personal experience. I personally hope that we get to see this person again, and they're not just a throw-away character. I also wanted to point out that the character's voice was well-written, though I assume you just wrote the same way that you personally speak, and that's fine. The issue comes later on in the chapter when there's a 10-year time jump. The character continues to speak in the same exact way, but people can change A LOT in a decade. Consider changing up the syntax a bit, maybe making the character speak more formally or make them sound more mature. Other than that, it's a good prologue.
As for the next few chapters, they're pretty good as well. You introduced the main characters in a unique way, especially Jack. In the short time that Jack, Kana, and Lee interact, I can already feel them getting fleshed out. I would also like to commend how Kana and Jack use magic in a seemingly everyday situation, which gives slight hints about what magic can do while also keeping a fantastical tone. You even described the side characters in such a vivid fashion that I had no problem visualizing them. Overall, great character work. Keep it up.
For the plot, I can't really say too much since there are only four chapters. Personally, it would have been more exciting if the Monster Hunt happened a bit earlier, but I guess I'm just an impatient guy. I can see that you wanted to take the time to develop the main cast first, but there's a little bit missing when it comes to the Monster Hunt. Through exposition, you describe it as a huge event, but if nothing that ties it to the main characters, it won't feel huge to me, as the reader. Kana and Lee are just doing it because it's required (correct me if I'm wrong on this one since I haven't gotten the full context of the characters' personal lives yet).
I'll give a few suggestions for how to increase the reader's anticipation for the upcoming Monster Hunt.
1) What if Kana or Lee needs the fame from the Hunt so that they can make money to support a family member? This one's a bit cliche, but it still works well.
2) What if Kana is a crazed combat maniac who's addicted to hunting monsters?
Passionate characters are almost always compelling. For example, Ladd Russo from Baccano! is a psychopathic murderer, but he's so passionate about it that he's always an entertaining character on screen (if you haven't seen Baccano!, Ladd kills people all the time, and he has tons of fun doing so). Disclaimer: I don't condone murder.
3) What if Jack really wants to go on the Hunt to get famous, but his sister wants to stop him for his own safety? That creates an initial conflict and is more compelling than a character who doesn't want to participate in the hunt because he doesn't have to.
Those three suggestions are just a few out of dozens of possibilities. Your work is still in its early stages, so you have a lot of room to work with ideas. I don't want to write your characters for you, and I only gave those earlier suggestions to help you brainstorm.
Overall, your novel is great so far, and it has great potential.
