Shingo Onijima is a journalist bearing a rugged presence, branded by an "X"-shaped scar across his left cheek—a mark that earned him the moniker "The Black Wolf of the Manchurian Steppe." His left eye was maimed during a childhood act of bravery while defending a girl he loved, an ordeal that forged his resilience and unyielding loyalty, profoundly shaping his worldview and future choices.

He forges a steadfast bond with Shinobu Ijuin, anchored by a debt rooted in their shared history during Manchurian turmoil, though the specifics remain entwined with their experiences there. His connection with Tamaki Kitakoji blossoms into a secondary romance, defined by mutual reliance and deepening emotional ties.

Professionally, he champions feminist causes, vigorously supporting Benio Hanamura’s quest for autonomy as she navigates restrictive early 20th-century gender roles. His wartime endeavors in Manchuria draw upon his dual identity as a battle-hardened strategist and warrior.

His narrative arc delves into themes of sacrifice, loyalty, and reckoning with past wounds. Later challenges emerge as he grapples with Shinobu’s disappearance and its emotional aftermath, yet he remains devoted to Tamaki. His journey oscillates between a steely exterior and an undercurrent of compassion, most evident when defending the vulnerable or challenging societal inequities.