In a not-so-distant future, nations invest heavily in scientific research to address food shortages. This leads to the discovery of new elements beyond the 119th. Tokyo scientist Hikojuro Araki creates Araraginium, the 256th element, capable of generating life from nothingness. However, during the inaugural experiment, an unexpected accident scatters Araraginium across Tokyo.

Days later, a strange phenomenon occurs: individuals presumed dead reappear, retaining memories from before their demise. Dubbed Araragi Humans, they emerge from the period between the accident and 72 hours prior.

This story unfolds in Tokyo years later...