The manga follows "Corona-kun," an anthropomorphic version of the new coronavirus (COVID-19). The story is set in a world where humanity failed to contain the virus and all life and culture perished. Corona-kun looks back on history and asks what humanity could have done to survive while making amusing observations.

In the first chapter, Corona-kun discusses the 1994 action thriller film Léon: The Professional and remarks that the hitman protagonist lived an ideal self-isolating lifestyle by avoiding human contact and only ever going out to do his job. He may have eventually met his demise through fighting for a young girl's sake, but, as Corona-kun reasons, he would never have died if he never made contact with Mathilda. [ANN]