Genuinely, this manga is so fucking weird, there's so much going on the doesn't connect or...

Were you not paying attention? She said she was for practice.

1. Just a theory of mine: I think she was perhaps the mc's crush however he doesn't remember. She probably did something to him and she somehow got into some shady business. That would explain how she was wearing a highschool outfit while being in I think college I don't remember. She was filming an adult video however got kidnapped or maybe cosplaying is just her hobby.

2. Refer to 1

3. I have a theory (this probably isn't true tho) that the kidnapper was actually the best friend. He might have staged his own death. Or maybe the friend was actually someone the kidnapper killed in order to have the mc to himself.

4. He probably saved the kidnapper from killing himself or something like that. I mean the guy looks super shady it would be no wonder if people bullied him. Perhaps in a moment of kindness the mc helped the kidnapper however forgot.

5. Well I think it could be two things. One it could be the kidnapper messing with the mc that way it could get him distracted in the past. Or it could be that an incident happened that caused him lose some memories. That incident may have caused him to get bullied by the people.

6. Idk he probably did something shady to get all that money or he was born rich.

But hey that's just a theory! A game theory!

1- Some of those make a lot of sense, we'll see how that turns out

2- I'm just still curious about how everything interconnects

3- That game theorists reference made me smile, thanks for that!

But can she be trusted on that though? While he was sleeping she did that shady-as-hell apology for a very much unknown reason and she's clearly there for more than practice. There's too much shady stuff surrounding her to be just there for practice.
If she was only a practice kidnapping then:
1- Why is she still there? That crazy bastard probably would have disposed of her like he did to that bully at the start. If she's still there, there's a reason.
2- Why the apology? Again, there was that apology even though she has seemingly done nothing wrong.
3- Why let her interact with mc? If she was just practice there was no way he would let her interact with mc. Everything he's done or exposed mc to up to this point has been for a purpose of his own, except Hayan who seemingly is just there. That doesn't fit considering the only human contact mc has had apart from her is people the crazy guy wanted to use to manipulate or use mc for something. I highly doubt that constant contact with such a seemingly sweet girl is something that he would allow. So she is there for a reason and agenda of the crazy guy's, she has to be.

Her being just practice makes no sense as to her presence in the plot at all, so there has to be more to her.

He could have left Hayan there to take care of protag. She is also easy to use for bargaining, protag is careful about disobeying because he knows that Hayan could also be punished and antag might use that to his advantage. Hayan keeps him in place. She definitely has a use, I don’t know if it’s her fault tho. But nice characters are always suspicious in situations like this so I don’t blame you.

I think (this might be wrong idk) In the future the mc will be given a choice he can let Hayan go but the mc will stay or the mc can leave but she will stay. I think the reason she said sorry was because she was going to do anything even manipulating him into making him choose her.