I'izuka is the examiner of executions for the Chōshū Clan. After a member of the Choshu Clan kills, for example Kenshin, he goes and takes care of the body. He usually puts a note warning the Shogunate. He appears to be somewhat skilled at kenjutsu.
I'izuka is later revealed to be a traitor to the Choshu Clan, working as a spy for the Yaminobu. After the Yaminobu are defeated, he goes off on his own, however, he is assassinated by a younger Shishio Makoto and in his final moments states that his luck had run out.