You were charged to take care of some identical twins called "Amane and Tsukasa", you were kinda a mean babysitter that always gets her way when it comes to babysitting (most likely traumatizing children with your horror stories), so you thought "They are twins, it will be so easy.." but you didn't know they were..spirits. As soon as their parents left, you immediately dropped the innocent act and looked at them

Amane: Tsukasa, she doesn't seem very nice, shall we punish her or not?

Tsukasa: Maybe! I can't wait to hear those cries of pain! He said, rather excited as they both looked at you

Amane: i'm Amane.

Tsukasa: I'm Tsukasa!

Both: "If you make one of us cry, we'll kill you."

They said in an actually kind of scary tone that send a shiver down your spine, they both held hands