Kiyotaka Ijichi serves as the assistant director for the Tokyo campus of Jujutsu High, a position that places him in charge of all auxiliary managers and makes him a central figure in the logistical and administrative support of jujutsu sorcerers. He was born on April 20 and is in his late twenties. Ijichi attended Tokyo Jujutsu High as a student with the initial goal of becoming a full-fledged jujutsu sorcerer. However, he was strongly advised against this path by his upperclassman, Satoru Gojo, who told him he was not suited for combat and suggested he get a driver's license instead. Ijichi took this advice to heart, shifting his aspirations from frontline combat to the crucial support role of an assistant manager, a decision he later realized likely saved his life.

In his professional capacity, Ijichi is calm, rational, and reserved, maintaining a composed and authoritative demeanor. He is a highly responsible and mature individual who takes his duties seriously, overseeing the logistics of missions, briefing young sorcerers, and ensuring the secrecy of jujutsu activities. He is genuinely dedicated to the safety of the students under his care and is deeply affected when any ally is lost. He felt significant regret after Yuji Itadori was killed during a mission at a detention center and later tried to prevent Yuji from rushing into danger again. Despite his professional exterior, Ijichi’s personality shifts to one of visible nervousness and anxiety around those he attended school with, particularly Satoru Gojo and Kento Nanami. He constantly fears being punished for making mistakes, and Gojo's playful, rule-breaking attitude and backhanded compliments cause him significant stress.

A key aspect of Ijichi's motivation stems from his complex relationship with Gojo. For a long time, he believed Gojo thought he was useless, even feeling that Gojo would have preferred him to die instead of Nanami during the Shibuya Incident. However, as the story progresses, he comes to understand that Gojo's harsh words were a misguided attempt to protect him from a dangerous life. This realization culminates when Gojo entrusts him with a critical task, stating that Ijichi is the man he trusts the most. This profound show of faith motivates Ijichi to put his life on the line to live up to the expectations of the strongest sorcerer.

Ijichi's role in the story is almost exclusively that of a non-combatant support specialist. He is frequently seen driving sorcerers to their destinations and setting up Curtains, barrier techniques used to conceal jujutsu battles and cursed spirits from the general public. He is highly knowledgeable about jujutsu and mission protocols, making him an invaluable asset for guiding students and coordinating operations. His ability to oversee and direct multiple teams of sorcerers and managers was especially critical during large-scale incidents like the Shibuya Incident, where maintaining communication was a matter of life and death. His most notable practical skills are his administrative ones; he is exceptionally proficient with office work, particularly Excel, and handles everything from financial management to data editing and government liaison. While he can conjure shikigami and has enough training to exorcise a low-grade curse, he lacks an innate cursed technique and is technically forbidden from engaging in direct combat.

His key relationships define his place in the jujutsu world. His dynamic with Satoru Gojo is the most significant, evolving from one of intimidation to one of mutual trust and respect. He shares a professional and respectful relationship with other sorcerers like Nanami and Shoko Ieiri, as well as with the students, especially Yuji Itadori, whom he feels protective of. Among his fellow auxiliary managers, Ijichi is a respected and reliable leader.

Throughout the series, Ijichi experiences notable development. A pivotal moment is his decision to stand his ground against the curse users Nanako and Mimiko Hasaba after they had just murdered several managers, attempting to talk them down despite his fear. During the Shibuya Incident, he was ambushed and critically stabbed by the curse user Haruta Shigemo, surviving only because Nanami found him in time and Shoko Ieiri used her healing abilities to save his life. In the final Shinjuku Showdown, Ijichi overcomes his long-held insecurities and plays a crucial role by setting up a barrier that deceived Ryomen Sukuna about the nature of Gojo's opening attack, allowing the sorcerer to land a devastating first blow. This act cements his value and shows his willingness to risk everything for the cause.