An overworked salaryman stepped off at a wrong train station by accident and soon found himself in a town that is as charming as a picture book with all of his memory gone. Soon after he settled down in that town, he started receiving letters from people claimed to be his parents, his wife and even the prime minister of Japan begging him to come back. At the same time, mysterious beings that look like white clumps started showing up on Earth. Living beings may die when come into contact with them or turn into them if they somehow ingest the white clumps, no matter how little the amount. Many species became extinct. Human population dropped to a tiny fraction of prior level. Scientists believe that the salaryman is the linchpin to the crisis on Earth.
I like the way this book depicts the huge number of people and countries involved in tackling the crisis, each contribute to the cause in their own various way, and these people may not even know each other, unlike most LN or manga where crises are resolved by a small group of people or even chiefly by the MC. So the crisis management here is a long and torturous path, with a lot of setbacks along the way, which makes it refreshingly realistic. Also, reading this book makes me question myself whether I would give up a perfect life and my own life to save a place and people that I have no memory of.