The world is stunned when a group of time travelers arrive from the year 2051 to deliver an urgent message: Thirty years in the future, mankind is losing a global war against a deadly alien species. The only hope for survival is for soldiers and civilians from the present to be transported to the future and join the fight. Among those recruited is high school teacher and family man Dan Forester. Determined to save the world for his young daughter, Dan teams up with a brilliant scientist and his estranged father in a desperate quest to rewrite the fate of the planet.

高中二年级的春季，主人公高宫菜穗 收到一封10年后的自己寄来的信。信上把未来会发生的事情告诉了菜穗，为了让菜穗不要像自己一样做出“后悔的事情”，信上指导菜穗应该采取怎样的行动。而10年后的菜穗后悔的事情就是，没能挽救高二时喜欢的成濑翔 的生命 。于是菜穗决定改变命运，然而翔虽然也喜欢她，却因母亲自杀心很受伤。究竟如何去做才能改变翔的命运，为此菜穗开始努力付诸行动 。

As the end approaches inexorably, the last humans, living millions of years into the future, send a message to the humanity of the present that is both a plea for help and a warning, but also an epic tale of evolution, decline and hope.

After an open mic night, JB and KG get a message from Michael Keaton who tells them that the time-space continuum has been disrupted at the Ford's Theater in 1850 and only Tenacious D can fix it.

Sixteen-year-old Logan is an adolescent uncomfortable in his own skin. Only his science fiction dreams of a better life on Mars draw him away from his ordinary life, which is as equally difficult at home or at school, where he's only seen as an aggressive loser. One evening, he receives a visit from a mysterious man who insists that he has come from the future and that he is also Logan, but forty years older. He then asks the younger Logan to carry out a mission as unexpected as it is important: to save humanity.