Parents' anxiety is growing as a series of incidents occur in Japanese schools where foreign substances are put into students' personal tumblers. As cases that cannot be considered simple pranks recur, educational authorities are changing storage methods and even related safety products are gaining popularity. According to Aera, a weekly magazine affiliated with the Asahi Shimbun on the 13th, at an elementary school in Suginami-ku, Tokyo, in February and March 2024, students were drinking drinks in their own tumblers and spitting them out after sensing a strange smell and taste. The drink reportedly had an odor similar to detergent or soapy water. Similar incidents occurred at other schools. Last September, it was revealed that a student at an elementary school in Adachi-ku, Tokyo had put a sleep-inducing drug in another student's tumbler. In addition, cases of adding rubbing alcohol or magnets have also been reported. As the situation continued, the school site also began responding. The Suginami-gu Board of Education ordered students' tumblers to be collected and stored next to the teacher's table instead of being placed in lockers at the back of the classroom. When moving between classrooms, students were asked to carry it with them.