Koori Ui

Koori wears his black hair in a sleek bob that reaches toward his chin, with a fringe cut level at the eyebrows to frame his large, near-black eyes. His skin runs pale, and though he is slim like other young investigators, his build is wiry and clearly strong. Standing around five feet seven, he cuts a somewhat androgynous figure. He favors tight, usually black suits, swapping to the white trench coat of the Arima Squad when on the job.

Koori keeps a fairly relaxed manner and will crack jokes even amid tense fights, yet he shows real insight when reflecting on the cost of an operation. After the timeskip he burns with a firm sense of human justice and treats Haise Sasaki warily, convinced no ghoul can genuinely be good-natured. The deaths of his closest friends grind on him, driving him to question what he is even fighting for. When Kichimura Washuu dangles the possibility of reviving Hairu Ihei, that grief turns him ruthless and detached, willing to ignore the CCG's corruption in pursuit of Kichimura's goal.

Koori takes part in Special Class meetings despite his lower rank, then joins the Owl Suppression Operation, holding his ground against the One-Eyed Owl until the creature forces him to borrow one of Kousuke Houji's heavy quinque and finally knocks him from the fight. Promoted to Special Class over the timeskip, he leads the S1 Squad and oversees the Tsukiyama Family Extermination, entering the estate alone to demand Mirumo Tsukiyama's surrender. The operation ends in disaster when he discovers the corpse of his partner Hairu Ihei and, moments later, watches Sasaki devour the One-Eyed Owl's kakuhou in stunned disbelief.

The failure lowers his standing, and losses keep mounting through the Rushima Landing Operation, where he battles Shuu Tsukiyama and the Black Dog, Kaya Irimi. Afterward he confides that he has lost everyone who mattered, Arima, Hirako, Hairu, and even Sasaki, and no longer knows what he fights for. During the Clown Siege he coordinates the defense of the branch offices, clashing repeatedly with Matsuri Washuu while entrusting the Main Office to Juuzou Suzuya.

His course darkens once Kichimura seizes leadership. Newly named Bureau Director Adviser, Koori watches in horror as Kichimura stages executions, employs Akihiro Kanou, and unleashes the Oggai children, realizing the CCG is finished. But when Kichimura reveals a jar holding Hairu's head and promises to bring her back, Koori is left speechless and pushes ghoul extermination toward total slaughter, ignoring Okahira's warnings against reviving the dead. In the final conflict he fights beside Take Hirako against the Dragon and is shielded by Juuzou during a devastating Owl attack. He ends up an instructor at the TSC Academy, training peace officer candidates. His skill set includes superhuman agility and refined swordsmanship, and he wields the koukaku quinque Taruhi, a halberd whose blade can extend into a whip, along with the SS-rated Ajite.