Muto was born in the Setagaya ward of Tokyo and graduated from Yokohama National University in 1972, where he studied economics.
[6] In 2017, Muto published his third book 韓国人に生まれなくてよかった (English translation: Fortunately, I wasn't Born a Korean) that mainly focused on heavily criticizing Moon Jae-In as the recently then recently inaugurated president of South Korea but also criticizing various aspects of South Korea as a whole.
In the book, he said described Moon as "the worst president ever elected in South Korea" and accused him of potentially using "anti-Japan" policies to boost his popularity.
Talking of the then recent mass protests moves to impeach and impeachment of President Park Geun-hye as “an act explicitly showing the ugly face (of Koreans) who are swayed by sentiment than logic" and additionally claimed Park became a target due to her attempts to improve South Korea-Japan ties.
Muto answered "Today, Koreans might see me as a Korea hater, but I have both love and hate for the country.