Back in 1975, an unsuccessful Japanese punk rock band called 'Gekirin' (Wrath) is dropped by their record company due to poor sales. Just before they break up, they record a final song entitled 'Fish Story'.

In 1982, a meek college student, Masashi (Gaku Hamada), takes interest in the record after hearing about a rumoured peculiarity with the song. Randomly, a mysterious lady at a party foretells that he will save the world.

Teenager Asami (Mikako Tabe) dozes off during a school field trip in 2009 and is left behind on a boat. As she is being consoled by a cook, an armed gang of men attempt to hijack the vessel.

In 2012, a massive comet visibly approaches the Earth. Attempts to destroy it at a safe distance have failed, and with only 5 hours left to impact, the streets are lifeless and quiet.

That is, except for one record store that is open for business as usual. And playing on an old turntable, the strains of 'Fish Story' can be heard.

Based on a novel by Kotaro Isaka, Fish Story weaves together several disparate occurrences taking place at different times over a 37-year span to explain how a little-known punk rock song might save the world.