A Thistle of Vengeance is the thirteenth chapter overall and sixth chapter of Higanbana no Saku Yoru ni - Dai Ni Ya (彼岸花の咲く夜に 第二夜).
When Yukari is transferred to another class, she sees a boy in her class named Masaaki Yoshikawa that is being bullied by the boys in her class. He says that he's not being bullied to Yukari but really he is getting bullied. After school, he sees Azami and She tells him that if he eats a magic thistle, then He'll get payback by bulling the boys. Sumire wants to get revenge on Higanbana but Higanbana is more strong and scary, so she changes her mind and wants to get revenge on Yukari for saying that bullying is not fun. One day, Masaaki steals an boy's pencil case by playing "tag" and the boy commits sucide. He tells everybody in his class that He fell on purpose but his classmates think that he's lying. He is once bullied again when the power in the magic thistle is gone. After school, Yukari calls Sumire and Azami. She tells the powerful youkais that She has to eat the thistle to stop bullying. One day at school, she slams her desk and the teacher's desk and she tells the whole class to stop bullying and She says that Masaaki is her assistant. At the end, Masaaki learns his lesson.