Ordinary college student Zack leaves the normal world every Friday, entering a world of dangerous Scenarios and Dungeons that pit him against both fellow humans and monsters alike.

The novelty of discovering he is a Returner is quickly lost when his future self informs him of why he has forcefully returned—he is destined to die within three months. Zack is as stubborn as a mule. He's not going to let that happen this time around.