A calligrapher who disgraced himself by punching a director of an art gallery who criticized his calligraphy style heavily as "boring," "rigid," "academic," and "bland." He then leaves for the Goto Islands in Nagasaki at the suggestion of his famous calligrapher father to focus more on his calligraphy as he waits out his "exile." Along the way, he finds value in interactions with other people, in particular a tomboyish little girl named Naru, and finds his inspiration and own personal style. At first, Naru calls him "Junon Boy," referring to a particular magazine that features street pictures of male idols, suggesting (incorrectly) that he's a city-dwelling pretty boy of the kind that don't really exist in real life. Later on, she calls him, "Sensei." Sei Handa appears again in another manga titled Handa-kun, a prequel of sorts featuring Handa during his high school years. In the prequel, he is a well-regarded school idol and prodigy calligrapher who holds the hilariously mistaken belief that no one likes him and that the distantly worshipful actions of his peers is in fact bullying. This is apparently the fault of his best friend of both series, Kawafuji, who told him a lie that he was "hated" as a joke, which Handa mistook for the truth, and his friend never actually tried to correct because he found it funny and amusing.

Nishimiya's younger sister who is currently a middle school student. She cut her hair short so their mother would not cut Nishimiya's and has kept it that way ever since; due to this, she is often mistaken for a boy, with Ishida even thinking that she is Nishimiya's boyfriend at first. Yuzuru is extremely protective of her big sister and has a deep hatred of all the people who ever bullied her, in particular Ishida; however, upon learning that Ishida has changed, she mellows down, accepts, and even encourages him to go out with her sister, though she is frustrated of their reluctance to do anything about their feelings and never moving past their relationship as friends. Yuzuru often bunks off school to take photos of dead animals and insects, which causes her and her mother to not get along. (Source: Wikipedia)