Along with his partner Kamata, he is feared as Kamakura no Kyouken (The Mad Dogs of Kamakura). This duo were renowned for their brutality, including shoving pencils through people's noses.
However after being beaten by the Oni-Baku, the pair decided to join their gang.
Saejima has a malevolent face, so much so that girls are afraid of him and assume he is a Yakuza. He, like Ryuji, comes from a fairly well-to-do family, who are terrified of him- his sisters speak to him through a lock on their bedroom door, and his parents jump at his slightest movement. Saejima rides a Kawasaki.