Katsuya Tomita was born in 1972 in Kofu, Yamanashi Prefecture (Japan).
After high school, he moved to Tokyo to try to realize his dream of becoming a musician. But he spends his time watching movies and wants more and more to make films himself. He saves money to achieve this by working as a worker or as a truck driver.
For three years, with an 8 mm camera, he spends all his weekends making 'Above The Clouds' with his childhood friends as actors. This film receives in 2004 the highest award at the student film festival in Tokyo and is released in theaters.    
Thanks to this money prize, he writes with Toranosuke Aizawa 'Off Highway 20'. This movie depicts the lives of youth of Kōfu who have no choice but to find a meaning to their lives outside the city.
During this period, not discouraged by the lack of real means of production, he founded with his band 'KUZOKU a tribe of filmmakers', a collective that seeks alternative means (such as donations) to produce and distribute films in Japan. In 2008, with KUZOKU, he started his project 'Saudade'.
Funded mostly with the support of the people of Kōfu, 'Saudade' becomes in 2011 a fresco of nearly three hours, chronicle of his hometown and its inhabitants, most victims of the economic crisis, Japanese but also Thai and Brazilian immigrants.
Immediately spotted by the Locarno International Film Festival, the film won that year the Montgolfière d'Or award at the Festival des 3 Continents in Nantes and is invited by many other festivals - four of them, including the Jeonju International Film Festival in South Korea seizing the opportunity to organize a retrospective of his work.
From 2012, Katsuya Tomita began to divide his time between Tokyo and Bangkok to prepare 'Bangkok Nites', premiered in 2016 at the Locarno International Film Festival (International competition).