Tsutomu Ryuzaki

Ryuzaki receives limited direct characterization because his importance lies primarily in the investigation surrounding the serial murders.

Information about him is reconstructed through police work and the shared history of the people connected to the case rather than through an extensive personal storyline.

No specialized combat abilities, supernatural powers, or distinctive professional skills are established for Ryuzaki.

His relevance comes from his involvement in the past event connecting the serial murder victims.

Ryuzaki is among the people linked to the serial killings investigated by police departments from several jurisdictions. The placement of mahjong tiles at the crime scenes suggests that the murderer is deliberately connecting the victims.

Investigators discover that the victims were connected to a hotel fire in Kyoto two years earlier, during which Nanako Honjo died. The circumstances of that fire provide the apparent motive for the later killings.

The case eventually brings Conan into conflict not only with the murderer but also with the Black Organization, which has its own reason for infiltrating the police investigation.

Nanako Honjo is connected to Ryuzaki through the hotel fire that becomes the underlying link between the serial murder victims.

Kosuke Mizutani believes the people connected to the fire bear responsibility for Nanako's death and becomes central to the investigation surrounding them.

Conan Edogawa investigates the pattern connecting Ryuzaki with the other victims.