Graduated from Kyoto University, Faculty of Economics. After working at the Bank of Japan as an Economic Analyst for 6 years, Matsugae left the bank and formed a theatrical troupe. He was discovered by Hiroyuki Nasu, a film director who came to see a stage play of his troupe. After that, Matsugae wrote a screenplay based on "God's Left Hand, Devil's Right Hand", a work drawn by Japan's popular comic artist Kazuo Umezu. First, it was planned to become a movie directed by Hiroyuki Nasu, but because of the director's unfortunate sudden death in February 2005, Shusuke Kaneko, a friend of Nasu, took on the director's position, and the movie was eventually finished and released. After this movie, Matsugae worked as an assistant for Shusuke Kaneko and was involed in the production of the movies "Death Note" and "Death Note the Last name".