Kazuki Kurauchi serves as a B-Rank Border agent and Shooter in Ōji Squad, partnered with combatants Kazuaki Ōji and Yutaka Kashio, alongside operator Haya Kittaka. Previously, he belonged to Yuba Squad under combatant Takuma Yuba. He stands tall with brown hair meticulously slicked sideways and parted centrally, often maintaining an expressionless face. On duty, he wears Ōji Squad's standard uniform; off-duty, he favors collared or collarless shirts layered under open black blazers.

Calm and collected, Kazuki methodically analyzes situations to craft strategic plans during missions. Despite his outwardly robotic stoicism, he possesses deep emotional sensitivity, easily moved to tears by poignant films or events. Outside Border, he holds the student council presidency at Rokueikan High School, earning him the nickname "Prez" from peers like Atsushi Hokari and Sumiharu Inukai. His extensive, passionate expertise in Triggers is exceptional among agents. During Round 8, he dissected Yukari Obishima's technique, pinpointing Grasshopper's vulnerability to Trion bullets and proposing countermeasures.

Academically, Kazuki plans to attend Mikado City College, drawn by its specialized Trigger studies program. He prefers green tea over sea bream rice, oyakodon, and pickled turnips, and enjoys visiting aquariums. Photography is a dedicated hobby, with select framed works displayed in Border's operator room. An unverified rumor suggests a romantic involvement with Haruka Ayatsuji, his student council vice-president, though he denies this claim.