Maou Reijou no Shikousha - Vol. 1 Ch. 1 - For the Sake of Someone

[NicholasTurner]

I think his classmate (creator girl) tried to kill him, she said he should break the charm and it will unleash helpful magic but when he broke it on the monkey it exploded in an icy vortex meaning if he broke it himself like she said he would die.