The Matsuno sextuplets attend their high school reunion and feel embarrassed by the success of their former classmates who have "proper" jobs, relationships, and families. Feeling like failures, the NEETs return home and drown their sorrows with alcohol. As they drift off into unconsciousness, they suddenly find themselves in a strange world of memories - all revolving around one of the brothers' biggest regrets from high school. As they explore this memory world, they come across their past selves, as well as old friends, all while trying to figure out whose regret caused them to become trapped in this alternate reality. Time is running out as this unstable world could crumble and they may miss their chance to fix their past mistakes.