A third-year transfer student and new chief of the patents development division, A-TEC. He is the younger brother of Kazuhisa and Yuuji. After having a large amount of corporate success in various tasks around the Solar System, the company brought him to Mars to handle the disbanding of the A-TEC division.

Nagisa is actually a child from his father and a woman named Shinamiya Chisato, the only blood relative that Shinamiya Reinchiro has; thus, making him the legitimate heir of the Kirishina Company.
He is actually a son of the Shirasaki family who serves the Shinamiya Family.
(Source: Wikipedia)