Kanojo no Sekai - Vol. 1 Ch. 2

[MangaDex]

 

[lluNhpelA]

"Though she's pitiful, it's somehow pleasant"

So Natsuki seems to be jealous of Yaneya-sensei and is lashing out as a result, though I can't tell quite how much of her behavior is premeditated maliciousness and how much is poor impulse control

 

[Mithgol]

poor impulse control

That was one hell of a poor impulse control! — if not for the plot armor, it would have carried a risk of driving the blackmailed person to suicide.