Haguro, a Myoukou-class heavy cruiser in the Fleet of Fog’s First Oriental Fleet, maintains a Mental Model mimicking a young girl with short dark-red twin pigtails and amber eyes. Her asymmetrical uniform—a modified school outfit she resents—clashes with her preference for her original attire. Exuding a childlike demeanor, she frequently voices reluctance or irritation when pressured to comply with orders or conform to expectations.

Deployed alongside sisters Myoukou, Nachi, and Ashigara to pursue the I-401, Haguro’s vessel is crippled during combat by a decoy submarine armed with corrosive warheads, severing her hull and sending her plummeting. Reduced to her Union Core, she signals desperately for aid until a shark swallows the core. Ashigara later recovers it, supplying nanomaterials to rebuild her Mental Model.

Post-reconstruction, Haguro and Ashigara breach the I-401’s engine room, coerced into aiding its crew under Iona’s persuasion when threatened with mutual destruction. Assigned to assist technician Sou Oribe in systems operations, Haguro contributes to the battle’s resolution. Stranded near Iwo Jima afterward, the pair face Hyuuga’s automated defenses.

Though deferential to flagship Kongou and Hiei, Haguro displays less overt loyalty than sister Myoukou. Her tactical coordination with Nachi, often underestimated, proves insufficient to halt the I-401. Forced into a provisional alliance with Blue Steel to survive, her enduring allegiance stays anchored to the Fleet of Fog despite circumstantial compromises.