Gen Isurugi is the younger brother of Isurugi Jin. Aside from Moroha, he's the only Savior in their class who can open all his prana gates; apparently, he started to practice using prana two years prior to his enrollment, explaining his advanced abilities compared to most of his colleagues. It took him a full year to open all his prana gates.
He harbored jealousy towards Moroha due to his popularity with the girls in the class, despite having roughly the same ability to open prana gates in his body. Right after defeating Satsuki, Moroha came to challenge him to a duel, which Gen ultimately lost.
He is very impatient and arrogant, as he demanded the teacher give him the advanced lessons in class. He has shown to be very violent as shown when he bullied Satsuki Ranjō and embarrassed her in front of the class. He also extended this treatment to Moroha Haimura when he noted of the latter's lack of power and was this way when he was overpowering him. However, his arrogance led to his defeat as his relentless attacks caused Moroha to awake his true power and easily defeated Gen.
He does have some respect for those who stick up for others, as shown when he stated this to Moroha after he was confronted by him and the latter demanded he apologize to Satsuki for his actions.