Itsuki Kujō is a student at Osaka Gakuen, the all-boys school where the story takes place, and he is a member of the First Dormitory. He serves as the deputy to Megumi Tennōji within the school's Karate Club, holding a position of some authority. Physically, he is depicted with grey hair and blue eyes.

In terms of personality, Itsuki presents a friendly and amiable exterior to those around him. However, this pleasant demeanor belies a more intimidating side, as he is known to be feared by nearly everyone when he becomes angered. The protagonist, Mizuki Ashiya, initially forms a poor impression of him, but he is ultimately revealed to be a genuinely kind and nice person.

Itsuki's role in the story is primarily as a supporting character within the school's social fabric. He participates in key school events, such as the dance between Osaka Gakuen and the girls of Saint Blossom School. At this event, he appears as the date for a student named Kadoma, and he also acted as her dance partner during the rehearsals. In another notable episode, when the pipes burst in the first dormitory, Itsuki ends up staying with the students Shuichi Nakatsu and Daiki Kayashima. This situation proves particularly awkward for Nakatsu, largely because of the first dormitory's tradition of washing each other's backs.

Regarding key relationships, Itsuki is closely associated with the karate club and its leader, Megumi Tennōji, whom he serves directly under. His primary interactions with the main cast often occur in group settings, such as the school dance and the dormitory incident. Detailed information about his personal motivations, his own character development throughout the narrative, or any specific notable abilities beyond his standing in the karate club is not available in the search results.