Sajima is a dazzling guy that convinced that multiplication tables are essential for survival.
He would later became obsessed with Suzuran's history claiming that all of the successive generations are his heroes and that if they were printed on posters he'd hang them on the walls of his bedroom .
His dream then became to enter Suzuran High himself and test his worth as a man.
A former member of the Hana-Gumi, he didn't mind being just another pawn on Hana's chessboard as he believed in Hana's leadership of Suzuran. He later appointed himself Tuskishima Hana's personal bodyguard.
Sometime later during the war with The Manji Empire, Sajima loss his title of strongest freshman to a new transfer student at Suzuran named Rocket . This loss leaves Sajima in a mild depression, due to having high hopes of competing with his fellow rookies, Todokin of the Armament and Mikuni Yuukyou of Housen.
Sajima later challenges Rocket again, this time handing him a decisive defeat, however he suspects Rocket lost on purpose .
Later when Rocket looked down on Suzuran by calling it a "trash heap", Sajima takes it upon himself to lecture him on the school's finer qualities.
In his second year, Sajima along with his faction looked on as the final fight of that year's Freshmen War.
In his senior year, he was seen hanging out on Suzuran's rooftop along with Rocket and Moriken.
The incident where he tripped and fell down the stair after being challenged by Ippin, caused Rocket went berserk and engage Ippin in a fight as he thought Ippin pushed Sajima down the stair.
- Sajima vs. Moriken - Won 
- Sajima vs. Rocket - Lost 
- Sajima vs. Rocket - Won, Rocket purposely lose