In his story Murakami uses the character of Frog as a wake-up call for Japanese citizens to a life style that is not conducive to anything valuable, representing the average citizen in the character of Katagiri. Katagiri is a office worker that has no friends, is depressive and works by the rules, with no purpose in life but only to work. Frog sees in him an extraordinary and respectable man, because he has sacrificied himself for the benefit of others p, with no rewards of any kind. Frog asks Kitagiri for his help to fight Worm, who is prepared to cause an earthquake and destroy Tokyo. Kitagiri has nothing to lose, and it is this dreamed fight against the inevitable and unpredictable to save others that brings meaning to his life.
I think Murakami is trying to tell something to the Japanese audience: that they live with earthquakes, there is no escape from it, and the imminent danger and the caring of others have to be their motivations to carry a life full of meaning. That is what happened after the Kobe earthquake in 1995. People stopped their work and study and went to help rebuild the city and community of Kobe, and in doing so, found each other and a community where people were able to meet and share experiences. No longer were Japanese just focused on their work in the office, but the earthquake made them realize the importance of living for something else, not just themselves.