The de facto leader of Freemum. He and his comrades seek to live freely without discrimination against Minimum Holders. For this purpose, he along with his 'family' join forces with Art.
Ishigami is a tall, slender man with a very casual appearance. He is seen throughout the series so far with the same outfit. Messy black hair that sweeps to the left, three piercings on his left ear and a slight scruff goatee. He wears a suit consisting of a black coat, maroon-ish long sleeve undershirt, black pants, and black shoes. A signature item for his appearance is his short blue scarf.
Ishigami is a very cool leveled, reasonable speaker as when he first met Birthday and Ratio for the first time. He keeps a serious expression half the time but smiles every so often and can make light humor.
At the beginning of Re: Hamatora, he appears to be very passionate about Minimum holders having freedom and a safe haven. It is insinuated from his claims that he might not even want his own Minimum and is waiting for a 'Savior' to help them.
However, later on, it appears that he is very much out for his own gain.
He was accepted by Art and founded the Organization "Freenum" with many other minimum holders. He believes that the minimum holders should have the same fundamental rights as the regular people of Yokohama, very similar to the view of Art himself, the main difference is that Ishigami wishes to achieve this through domestic terrorism, meanwhile Art wants to achieve through the destruction of all minimums.
Near the end of the series, he hacks onto the television network and traps all Yokohama citizens inside a death wall created by another minimum holder with a rapping Minimum. In term, he threatens the city that if his wishes aren't granted, an entire group of citizens will be sacrificed. Before the citizens are killed by the death wall, Art steps in, saving the citizens, brutally defeating two of Ishigami's enforcers before pointing a gun at him. Before shooting him, Art alas reveals he never liked Ishigami, and that people like him "make his blood boil".
After Ishigami was killed, a worried Hajime quickly puts the Rapper down and sets Yokohama free once again
His Minimum's ability is to make any sort of liquid boil. It is seen that he is able to make blood and water boil. He activates his ability by smearing blood under both his eyes.