Kazuki Honjo

Kazuki is serious and deeply concerned with matters involving his family. His participation in the case is driven less by abstract interest in the murders than by their connection to Nanako.

He is understandably emotional when discussing the events surrounding his sister, but he is able to provide investigators with information relevant to reconstructing the older incident.

Kazuki has no established supernatural abilities, combat specialties, or professional investigative training.

His importance to the investigation comes from his personal knowledge of Nanako and the people connected to the case rather than any specialized skill.

Kazuki becomes involved as Conan Edogawa and the police investigate a sequence of murders occurring across several prefectures. The victims appear unrelated until investigators discover a connection to an earlier event.

Nanako's death in a hotel fire becomes the common link between the murder victims. Kazuki's relationship with her consequently makes him relevant both as a source of information and as someone investigators must consider while examining possible motives.

The investigation ultimately reveals that Kosuke Mizutani, Nanako's boyfriend, has been pursuing the people he believes responsible for abandoning her during the fire, while the full circumstances of the killings prove more complicated than they initially appear.

Nanako Honjo is Kazuki's younger sister. Her death during the hotel fire gives Kazuki a direct personal connection to the serial murder investigation.

Kosuke Mizutani was Nanako's boyfriend and therefore knew Kazuki through his relationship with the Honjo family.

Conan Edogawa becomes involved in reconstructing the incident that connects Kazuki's family to the murders.