Having successfully defeated the Moja Corps, the LocoRoco settle back in their peaceful life. However, Bon Mucho, the Moja Boss, is not willing to accept defeat, so he devises a terrible song that can suck the life force out of living things, as a new attack on the LocoRoco.

The Last Guardian’s story is framed as a flashback told by an older man recounting his experience as a young boy meeting a giant, feathered creature named Trico. The name of the creature can be taken to mean “prisoner”, “baby bird”, or a portmanteau of “bird” and “cat”.