Syuu Aiba is a fighter pilot first introduced in custody, who is released to join a team fighting hostile entities called Hadeans. The character perishes in combat when their vehicle is disabled. After death, scientist Rurika Yuno resurrects them using an artifact known as the Book of the Dead.

This resurrection transforms the character into the Necrodiver, a prophesied savior of humanity. The process bestows new abilities, including the power to shape their arms into any weapon they touch. They also gain the guidance of three female spirits who help them master these powers.

Syuu Aiba previously served with the Neo International Defense Force (N.I.D.F.), an organization dedicated to investigating the Hadean threat and protecting humankind. The character exhibits a confident attitude and is recognized as one of the force's most skilled combatants.

Their appearance includes purple eyes, red hair with spiky bangs, and a tanned complexion. They are typically seen wearing gloves, a jacket, a tank top, and pants.

Following their rebirth, the character must adapt to their new role and powers while defending against enemies—both old and new—who seek to claim their abilities. The three spirits remain a constant presence, guiding them through this altered existence.