He is a student in Korosensei's class 3-E of Kunugigaoka Junior High School. Okajima is the class pervert and is rather open about it. As with Rio Nakamura, Okajima is known to like peeping. He likes to read erotica magazines and even claimed to be a brother of Korosensei and Itona Horibe for doing so. At the start of July, he enjoys looking at the girls' more exposed skin.