Monster is a 2008 directtoDVD Japanese daikaiju film.
The film takes place in Tokyo in 2003, where two reporters, Hana Izumi and Hyuga Kanata, have arrived to document unusual seismic disturbances that have been picked up around Tokyo. The disturbances are originally thought to be aftershocks left over from a supposed massive earthquake on the Kanto Fault that occurred two years previously, causing hundreds of thousands of casualties and several hundred billion dollars in damagepossibly referencing the reallife Fukuoka earthquake or the Miyagi earthquake, although careful analysis of the evidence suggests otherwise.As time goes on, all of Tokyo begins to suffer from abnormal earth tremors similar to those registered in 2005. The tremors are found not to be caused by an earthquake, but by a gigantic octopus that has been dormant for centuries. It has since been awakened by mankind and now sees Tokyo as a new feedingground the filmmakers document the catastrophe as it unfolds. ........
Source: Wikipedia