Light lives with the last remaining human children on a floating biosphere called the Ark which has become the last haven for humankind after most of the population, including all of the adults at the time, were killed. Light, his friend Joshua, and other children defend the Ark from mazoku using flying machines called gunpods, though modern technology is ineffective against mazoku. Though Light and Lina have the same last name, it has not yet been said if they are in any way related.