Rather than lewd, I doubt she even loves Akira, the player character.
I suppose Yanderes can be crazy, violent, hypocritical, and sadistic... I guess I wonder why Saiko is so crazy already.
Basically I missed all the lead-up and now I agree that Yandere doesn't fit as well as "Crazy sadistic murderer" does.
Also, she insta-kills after the safe is opened, so she really doesn't want him to leave the school... But why? Couldn't she just follow him? And is the school ever going to start again? Wouldn't it be better to take him somewhere more private? Maybe she isn't thinking that far.
The guy Akira spoke to.. So far, from the demo I played, the only thing that Saiko didn't like was Akira talking to that guy.
Maybe the explanation is just that she's batshit crazy already, where she has split personality, one is more regular, and the other has glowing eyes and wants to kill the character. The more regular one will repress the mad one, or I guess I can just call that Yangire mode, or mentally ill and angry mode, and the regular mode just Yandere, mentally ill and lovestruck mode.
That just returns me to asking why she's already screwed up, though.
Mmm... It feels like she already gave up on life. Not considering consequences, maybe that's solely focusing on Akira and being crazy. But giving up on keeping Akira alive...
Maybe Akira rejected her catastrophically? But she doesn't really mention that..
So... with the meagre amount of info I have playing the demo...
So Saiko would be already psycho and crazy as hell but barely maintains a normal-ish school life and falls in love at first sight multiplied by a trillion, and then immediately kidnaps him and the last person she saw talking with him, and then the events of the demo 2.01 version plays out.
Or maybe Akira was gay, and Saiko saw a confession between Akira and dead guy #1, and Saiko confronted Akira and maybe also confessed, then Akira rejected her terribly, and then she split her mind to bottle up the insanity, but by the time Akira gets the safe with the exit key open, Saiko's tiny smidge of sanity fades away or is beaten out by anger, and so she just stabs Akira to death, or she simply decided to have Akira dead if she can't have him alive.
Or maybe Akira was bullying Saiko, and so she was returning the favor, or 'love' in sadism in the short events of the game.
...Maybe she's just crazy and had a tiny remnant of sanity left that results in the passive mode at the start of the game. No explanation.
The messages written on the locker and the table are decent reflections of that fading smidge of sanity "I didn't want to do this.." written with the instructions on how to leave.
But why? Why? Why?
... It doesn't really need a reason, I guess. It doesn't need one. But I want one. So I imagined some.