Daiya Irma, codenamed Black Dog, serves as a secondary supporting figure in the series. Born in Republic Year 350, he is one year senior to most unit members and a year junior to Kaie and Kujo. His blond hair, blue eyes, and lean stature pair with weathered desert camouflage fatigues common among Spearhead Squadron personnel.

Though prone to social mishaps—like inadvertently disturbing female comrades bathing, prompting projectile retaliation—he balances this with emotional perceptiveness. He supports Kurena through moments of vulnerability and acknowledges Anju’s choice to grow her hair as a shield against trauma, offering heartfelt praise for her resilience.

Conscripted alongside Anju, their four-year partnership spans relentless deployments, deepening a bond rooted in mutual reliance and unspoken affection. Anju’s confirmed romantic interest underscores their connection, further mirrored in their codenames: his "Black Dog" alludes to European witch folklore, symbolically intertwining with her "Snow Witch" moniker.

As Fifth Platoon’s seasoned leader, he commands respect as a four-year Eastern Front veteran, hardened by the Republic’s systemic oppression and the erosion of prolonged warfare. His tenure ends during a mission where a Self-Propelled Mine inflicts mortal wounds, compelling Shin to administer mercy. His death marks the squadron’s eighth loss.

Survivors, particularly Anju, carry his legacy through memories of his empathy and their shared history. The folklore-inspired symbolism of his callsign and his role in uniting the platoon cement his enduring narrative impact despite his abrupt departure.