On Christmas Eve, three homeless people living on the streets of Tokyo discover a newborn baby among the trash and set out to find its parents.
In a society devastated by the effects of an all-out war between heroes and villains, a mysterious giant fortress suddenly appears, engulfing towns and people one after another. Then, a man reminiscent of All Might, the ‘symbol of peace’, stands in front of Izuku and his friends…
Shin-chan somehow travels back in time, where he promptly involves himself in samurai wars and political intrigue, changing history left and right!