Hanazawa Teruki is an esper who was first introduced as an antagonist, but later became Mob's friend after being defeated by him. He was the shadow leader (urabanchou) of Black Vinegar Middle School, using his psychic powers to rule over the delinquents at his own school, as well as to defeat those from other schools. After fighting against Mob and losing, he quit his shadow leader role. He is currently a second-year student at Black Vinegar Middle School.
Before meeting and fighting against Mob, Teruki was an arrogant and overconfident esper. Due to never having met an esper besides himself before, he believed that his powers granted him a special position above everyone else, calling them "commoners" and dubbing himself the protagonist of the world. He saw no problem with using his powers to get what he wanted, even if it meant using them against people. Knowing that Mob is another esper, and a powerful one at that, Teruki felt like his special position was being threatened, and tried to "erase" Mob's existence. After experiencing defeat by Mob's ???%, he came to realize that he himself is a commoner just like everyone else.
After that, Teruki tried to change his mindset about psychic powers, as seen in when he ran into Ritsu bullying some people from Salt Middle School with his newly acquired powers. It should be noted that while Teruki claims that he has changed, he still uses his powers against people, but only those who abuse their own powers for evil purposes. He also still maintains a confident personality, having great pride in his acquired humbleness alongside his other specialties.
Teruki is seen to develop an immense admiration for Mob and his powers after his defeat, and is willing to go to great lengths to help his new friend and rival out, sometimes at risk of danger to himself. He also possesses great respect toward Mob's master, Reigen, after seeing him at the Claw 7th Headquarters.
Teruki is a talented, quick-thinking, and hardworking esper. In terms of raw power, he is nowhere near Mob's level, but he compensates for this by putting in effort and training diligently. He is able to analyze other espers' techniques and their weaknesses in a short amount of time, and often incorporates said techniques in his own fights. He is constantly training to improve himself, and is remarked by various espers as possessing a keen and powerful set of skills.