Niji is the second oldest brother in the set of Quadruplets Vinsmoke Sora had, his brothers being Ichiji, Sanji and Yonji while his eldest sister is Reiju. Since birth, Niji has lacked the ability to feel empathy and sympathy, due to the genetic modifications performed on him by his father. Despite this there are very rare times where he expressed gratitude to those who've saved him. Nonetheless, hes apathetic and brutal.