Nagi Hirono is the older sister of Hiro Hirono and a former student of Otobane Academy, where she attended school alongside Yuu Himura and Shuuichi Kuze. She is a professional artist living in Otowa, Japan, with a natural talent for painting. Her brother uses her name as a pen name for his work as a mangaka. In the present timeline of the story, she has short brown hair, brown eyes, and wears glasses. Her personality is energetic and kind, though she has experienced periods of deep loneliness. At one point she lost her ability to draw, a condition that stemmed from feeling isolated. She later regained her artistic skill and eventually served as an art mentor to Yuu Himura, whom she loved during their high school years. Nagi was briefly engaged to Shuuichi Kuze and later became a friend of Mizuki Hayama. Her role in the narrative is that of a supportive figure and former classmate whose own emotional struggles and artistic journey intertwine with those around her. Her notable abilities are her painting talent and her capacity to teach and inspire others in art.