A class of high school students receive a text message welcoming them to a game where they are given tasks they must complete in 24 hours.

A high school class, containing 32 students, all receive a strange text message on their cell phones one night. It welcomes them to the "Ousama Game," in which they are given specific tasks to carry out in a 24 hour period. No one takes it very seriously at first, as the tasks are trivial things like having one student kiss another. Soon, the tasks escalate beyond what the kids are willing to do, and they learn that the cost of failure is death. Will they be able to find a way out of the Ousama Game before more people die, and the living lose their integrity and humanity through their participation in the increasingly horrible daily tasks?—bradleybarger

An endless apocalyptic virus-type game unless every player dies. If a survivor carries the virus, the game will never ends until humanity is destroyed. Now, An entire high school class of 32 people receive a message on their cellphones from a person known only as the "King." All of these messages contain orders that the students must obey, or they risk the punishment of death. With their lives on the line, the students soon find out that the orders are getting more & more extreme as time goes on. In the end, all 32 students were in the afterlife. The Game will never end...at all!—ryanting-28096

Kanazawa Nobuaki has transferred to a high school far from where he used to live. Due to an incident at his old school, Nobuaki is afraid of getting close to his new classmates and keeps himself at a distance, but he starts opening up because of a sports day inter-class relay. Then, a single text message from someone calling themselves the "King" is sent to everyone in class. Nobuaki's classmates think it's a simple prank, and don't take it seriously--but Nobuaki knows that a death game is about to begin, and struggles to oppose it.—Crunchyroll