Hiro Mizushima (?? ??, Mizushima Hiro, born Tomohiro Saito (?? ??, Saito Tomohiro) on 13 April 1984) is a Japanese actor, producer, writer, and creative director.
He appeared in a number of Japanese TV dramas, including Mei-chan no Shitsuji, Hanazakari no Kimitachi e and Zettai Kareshi.
Additionally, he was well known as the protagonist in the tokusatsu series Kamen Rider Kabuto.
Mizushima serves as the co-producer, co-screenwriter and leading actor for the latest film Black Butler which is the live-action film adaptation of the popular manga.
His birth name "Tomohiro Saito" is being credited as co-producer in the film.
Under his pen name Satoshi Saito (?? ?, Saito Satoshi), he wrote his first novel, Kagerou, which was chosen as the winner of the 5th Popular Publishing Grand Prize for Fiction and was published in 2010.