Itori operates the Helter Skelter bar in the 14th ward, which serves as her base for a thriving information brokerage business within the ghoul underworld. Her history is deeply intertwined with Uta and Renji Yomo, dating back to when Uta was the leader of the 4th ward. During that time, she was a member of his gang and would help lure ghoul investigators into traps. After Yomo arrived in the ward, the three formed a close and lasting bond, though Itori herself has described their relationship as undesirable yet inseparable.

In terms of personality, Itori presents herself as very friendly, talkative, and fond of having fun and playing pranks. However, this sociable demeanor masks a more calculating nature, as she tends to use people like toys to extract the information she wants. This duplicity is fully revealed when she is shown to be a member of the Clowns, a group of ghouls who thrive on creating chaos and destruction. In this context, she displays a cruel and sadistic side, gleefully discussing events like the CCG's goal of eradicating all ghouls. She also has a noted fondness for drinking blood, which might suggest she is a connoisseur similar to Shuu Tsukiyama.

Itori's primary motivation is rooted in her nature as a Clown. She, like her fellow members, seeks to orchestrate and revel in chaos and destruction for her own amusement, aiming to have the last laugh. This is driven by a cynical worldview; she believes the world is inherently biased towards humans, leaving ghouls in a cold void where they cannot feel warmth without inflicting pain upon themselves. The Clowns laugh from the shadows as a coping mechanism to avoid descending into madness from this despair.

Her role in the story is largely that of an information broker who provides key leads to the protagonist, Ken Kaneki. She is fascinated by him, referring to him by the nickname Kanekichi, and comments that he possesses a kind and pure heart that she and her friends have lost. Itori first aids Kaneki by offering to trade information about the Ghoul Restaurant for details on who was responsible for the steel beam incident that turned him into a half-ghoul. She later provides him with information about Dr. Kanou, the ghoul responsible for Rize's experiments, in exchange for a list of Cochlea escapees. Despite this transactional relationship, she expresses anger when Kaneki destroys the Ghoul Restaurant, as she was still researching it for her own benefit.

Her key relationships are central to her character. She shares a long and complicated history with Uta and Yomo. She affectionately calls Uta "U-chan" or "U-san," and there are strong implications that she has romantic feelings for him, though she may never have revealed them. She calls Yomo "Ren-chan," and their friendship endures even as they find themselves on opposing sides. In the epilogue, it is revealed that she, Uta, and Nico continue to try to kill Yomo every now and then while still maintaining their friendship, which is what Itori enjoys most.

Throughout her development, Itori remains a consistent agent of chaos. She observes and comments on how Yomo has changed since joining Anteiku, and during a later confrontation between Uta and Yomo, she anticipates Yomo's death, believing Uta cannot change unless Yomo helps him. True to her nature as a Clown, she is more of an instigator and spectator, seeking to watch the destruction unfold, such as when she suggests watching the destruction caused by Kaneki's kakuja rather than intervening to save him.

Regarding notable abilities, Itori does not display significant physical combat prowess. Her primary skill lies in her talent for manipulation and deception, which she uses effectively to run her information trading business. Her success in this field is noted by the many gifts she receives from her satisfied customers. She is also respected in the underworld for her work as a broker.