Shuu Izumi is the father of Kotori Izumi, a high school student entangled in parallel world events. As Genji Hazama's employer, Shuu oversees the scientist's interdimensional research. Genji, father to Shin Hazama, meets an unnatural death due to this work, directly linking Shuu to the escalating conflict across realities. Shuu's influential position, likely corporate or research-based, stems from managing advanced scientific studies. His daughter Kotori becomes targeted because her parallel counterpart rules oppressively, further implicating Shuu through both his professional ties to Genji and his familial bond with Kotori.