Little is known of his early personal life, other than that his family moved to the Tokyo area when he was nine years old.
Here he began working for Tokyo Puck magazine as a political cartoonist and manga series artist.
At the age of 26, Shimokawa was hired by Tenkatsu Production Company to create a short animated film.
At the time, celluloid cels (rather than modern acetate film) were costly and scarce in Japan, having to be imported.
Shimokawa's animation work was cut short by chronic health problems, and he returned to work as a consultant and editor for other production companies making animated films in the 1930s and 1940s.