Risa Yoshii

Risa receives limited independent characterization because her role is primarily part of the background reconstructed by the investigation.

Her importance lies in what she shares with the other people targeted by the murderer rather than in an extended individual storyline.

No supernatural powers, combat specialties, or distinctive professional abilities are established for Risa.

Her role is tied to the serial murder mystery and the earlier event connecting its victims.

Risa becomes relevant as police from multiple prefectures compare apparently separate murders and discover deliberate similarities between the crime scenes.

The investigation traces the victims' shared history to the hotel fire in which Nanako Honjo died. The people connected to that incident become targets because of the belief that their actions contributed to Nanako's death.

Conan's reconstruction of the older incident is necessary to understand both the apparent revenge motive and the inconsistencies that remain in the murders.

Nanako Honjo is connected to Risa through the hotel fire underlying the serial murder case.

Kosuke Mizutani becomes central to the investigation because of his relationship with Nanako and his belief that the people present during the fire were responsible for her death.

Conan Edogawa investigates the connection between Risa and the other people involved in the case.