Obviously, in the story, Yachio had mentioned that Lukari's a yandere.

That's basically true.

But, there are several anime characters her personality is based off as well...

Inuyasha is one of the anime characters, that's based off of her, and is what's given Lukari her stubborn side.

Like him, Lukari has the habit of wanting to do things her way but gets easily frustrated because she has no choice but to go along with someone else's plan.

Ayano Aishi, from the game Yandere Simulator, is another character that's based off of Lukari's personality.

Despite Lukari can only feel such tiny amount of emotions and getting really terrifying when angry or insane, is one good way to compare her to Ayano Aishi.

They're both pretty brutal when it comes to killing their rivals or hunting them down.

Not to mention getting information about their rivals as well.

Lukari's personality is mostly based off of Lapis Lazuli from Steven Universe.

They are both moody, have suffered horrible pasts, mysterious, and are incredibly strong.

But, Lukari tries her best on being kind to others even though she's a really sensitive character who does her best to keep her inner demon sustained.

Every character that I would've made a list of, has bits and pieces of Lukari's personality and who she's based off.

The dark side of Lukari's personality is a different story.

Think of someone who's cold-blooded, carries an atmosphere that'd scare the life out of you, never shows mercy to anyone, twisted, murderous, and who doesn't care what you'd say or do.

That pretty much sums up Lukari's dark side of her personality.
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*To shorten that by using a readers' commentary, Foxman237 (a.k.a WovenGold) described her as a monster from his point of view...Which is something I absolutely understand but clearly am not offended about.
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Lukari's dark side is something that I wanted the readers to take notice of the change in Lukari's personality.

Seeing her kind side one minute to unexpectedly seeing her violent side to the next.

What Lukari'll do in such different and very unusual personalities is mostly unpredictable.

The other characters in the story are completely unaware of what Lukari's capable of doing, even if Lukari was to possibly turn into a demon in the nearby future one day...

Nobody wouldn't realize it until it's too late when the situation is explained to them.

The only character who can easily predict what'll happen and how's Lukari gonna feel is mostly her children, and her husband, Yachio.

Just only him and no one else so far.

For Lukari to be put at ease when enraged, she has to be near her loved ones that she feels very close to.

It's like the "music soothes the savage beast" term.

At times when Lukari becomes a rogue to seek revenge and murder someone, she won't be calm until the killer is eliminated, as it says in the book.

But, to make this short and simple, Lukari has a dynamic personality.
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*Btw, you shouldn't worry. I've heard stuff that's more worse than that. ¯\_(^‿^')_/¯