Jinichiro Nishimura is a widower, his wife having died in a car accident two years before the main story. He is the father of Haru and Midori Nishimura. Jinichiro possesses fair skin, short brown hair swept to the left across his forehead, dark brown eyes, and wears dark, square-framed glasses.

His initial appearance occurs as Furuichi Teraoka informs Haru that Midori is safe, adding that Jinichiro will bring her to a shelter following the terrorist attack on Sentan Island. The next day, Haru asks Jinichiro to inquire at the hospital about a white-haired girl (Nazuna), a request he later forgets. While leaving the hospital, Jinichiro and Haru encounter Ryuzo Takehara, who has been searching every island hospital for his missing son, Akiyuki. Jinichiro does not appear again in the narrative after these events.