This is second book to the Transmigration series. The first one was Transmigration: The Cannon Fodder Beauty And Masked Beast.
This book is a stand-alone, so it definitely can be read without reading TTCFBAMB. Few of the characters in both the novels are similar, but without reading that, you will be able to understand this.
About Moon Jiwoo, if you have read TTCFBAMB, you might know how she is or what type of background she is originally from. But as for those who doesn't know, I will be explaining her background.
Her background is not important and you will eventually get to know about it. However, it is better to avoid confusion.
In TTCFBAMB, Moon Jiwoo was considered to be the 'Villainess' who wanted to go after the 'male lead' of a story Female Lead for TTCFBAMB had read, which is Ahn Eunwoo.
The female lead of TTCFBAMB had transmigrated to Jiwoo's body after Jiwoo's death, and Jiwoo transmigrated to Daerin's body.
Now, as for Jiwoo's personality, there is an explanation behind it. Jiwoo was an illegitimate daughter, but despite of that, she was not bullied inside her family.
Kids are influenced by the people around them, and usually that is how their personalities tend to turn out when they grow older.
Jiwoo's mom was the mistress to her father, and she abused and showed her arrogance around the mansion. None of her family members were close to her, and naturally, she could only copy her mom to learn her behaviour.
Her mom was not the one to care about teaching her daughter proper manners and basically her mom was like, 'If you don't bully and show your powers to other, they will not know their position.'
Jiwoo grew up being spoiled; she got what she wanted. She had inherited her temper and arrogance from her mother, and with no one to properly educate her on anything, she grew up to be like this.
If you have read TTCFBAMB, you would know that there was no one who liked Jiwoo. At school, she was laughed at by her classmates for being an illegitimate daughter, and therefore, she established her power at the school.
For Moon Jiwoo, who was lonely and had no one on her side, this was something she did to protect herself. Jiwoo vowed to herself on how she will never lose her pride.
When the entire world is against you, you can either fight back against them or let yourself get bullied.
Jiwoo's personality was not build over a day, and as for her impulsiveness and stupidity, it is because of how naive she is to certain things.
There is a deeper meaning to her personality. Remember, Jiwoo was considered a villainness once. That's the type of personality you will be getting from her.
Of course, there will be character development with her, but you got to be patient with that. It doesn't happen overnight :-)