Age: 23
Birthday: April 15

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.