The devil's app "333 APP (Triple Three App)" that anyone with an Internet ID can erase its existence forever. "333 APP" is suddenly installed on the smartphone of Yushin, a high school girl who has been targeted by cyberbullying due to a sudden chance. The owner of the app is called the "executor", and the rule is that if you do not delete someone within 33 days, you will be deleted. Yushin meets the boys and girls of the same executor, and they are invited to "use 333 APP for justice to eliminate the existence called social evil" ...!?