Hiro Kitazoe operates as a Gunner in Kageura Squad, currently ranked B-class after previously holding A-rank status. Standing at 189 cm, he ranks among Border's tallest agents, possessing a chubby yet muscular build, light skin, short spiky hair, a hooked nose, and small round eyes. His civilian attire typically includes light-colored loose sweaters, cargo pants, and heavy padded jackets, while his Border uniform features a double-breasted black military jacket with Kageura Squad's collar logo, paired with light gray cargo pants and black combat boots.

Emotionally expressive, Hiro frequently sheds tears during moments of joy or distress, such as celebrating teammates' personal growth or friendships. Despite this openness, he maintains a consistently laid-back and level-headed demeanor, remaining calm even in high-pressure combat scenarios. His personality evolved from reserved and conflict-avoidant to proactive and empathetic, influenced by former teammate Kuruma. This growth fuels his supportive squad role, where he reassures others during setbacks.

In combat, he specializes as a Gunner wielding a Trigger modeled after an MGL-140 grenade launcher—documented as a "grenade gun." His tactical approach employs calculated explosive firepower to support squadmates Masato Kageura and Yuzuru Ema, coordinated by operator Hikari Nire.

Outside duty, he owns a licensed motorbike and enjoys strawberries, spring rolls, donmono rice dishes, and mahjong. The series creator analogized him as "a lion who can gain weight" and a "lovable mascot," emphasizing his distinctive team presence. His interactions consistently provide encouragement and emotional support, exemplified by reassuring Kageura during struggles or expressing genuine happiness over teammates' milestones, cementing his role as the squad's emotional anchor.