Masato is a member of the Little Busters, and is Riki's roommate. He loves to work out and improve his muscle mass. His rival is Kengo Miyazawa, fellow member of the Little Busters. Masato is the most reliable and loyal of the Little Busters. He has a particular fondness for Riki, which he is more than willing to express out aloud. He's occasionally dubbed as "the lovable idiot."
In the artificial world, he supports Kyousuke's plan to strengthen both Riki and Rin to overcome the events in the real world, though he is less reluctant to put the two through hardships. However, he will side with Kyousuke when it really matters (as seen in the baseball battle against Kengo and Riki). The repeating events of the semester and what lies ahead have always been clear to him, but he always acts as his true self, never faltering, or at least never letting it show. Kyousuke even had to go as far as force Masato through hallucinations in order to isolate Riki and Rin from him during their first difficult test in Refrain (since he wouldn't have had the heart to antagonize them otherwise).
In the real world, he shielded Riki with his own body during the bus accident to save his life.
