“In order to survive, I have no choice but to kill!!”
Arisu is a high school student who faces bullying at school and abuse at home by her uncle. One day, she witnesses her uncle being killed by an assassin called "Arachnid." Thinking that she'll be killed next, Arisu has no choice but to fight back. Soon after, she wakes up at Arachnid's house, and he takes her in as his deadly apprentice.