Dr. Ishikawa is a supporting character in Nanako SOS who serves as an antagonist. He is a towering scientist with a physique reminiscent of Frankenstein's monster, complete with a striking ashen or grey complexion that makes him stand out immediately. As a mad scientist, he is part of a group of eccentric scientific minds who create trouble for the main characters. His primary role in the story is as an adversary to Nanako, with one of his stated goals being to kill her, making him a persistent threat throughout the series. To facilitate his schemes, Dr. Ishikawa commands a colossal and futuristic helicopter that he uses for transportation and likely for his operations against Nanako and her friends. He also has an unusual personal habit of being a voracious consumer of raw eggs. His character contributes to the bizarre and comedic chaos of the series, as he becomes involved in the strange incidents that Nanako must resolve. Dr. Ishikawa is also consistently identified as being part of a group of mad scientists along with his colleague, Dr. O.