Masaki Kawanabe had a close friendship with fellow seiyuu Takayuki Ishiguro of Tokyo Majin Gakuen. They shared an apartment together, and Kawanabe praised Ishiguro's cooking skills by saying that he was never left hungry. Some of Kawanabe's comic artwork was published in bulletins for the "Tokyo Majin Gakuen" FC. In addition to being a seiyuu, Kawanabe is also an actor who has performed on stage and appeared in TV commercials. He starred in the TV drama "Sayonara, Ozu-sensei," and was cast as Saitou in the live-action movie adaptation of GTO.