Lan Sizhui and Lan Qingyi

A report of terrible disappearances arrived in one of the cities.
Girls from noble families began disappearing one after another. Some were found dead outside the city, while others were never found at all.
The only thing they had in common was that they were all about sixteen years old, and they all came from wealthy families.
After the investigation, it became clear: the criminal specifically selects girls of a certain age and status.
Lan Sizhui, Lan Jingyi and Jin Ling were given the task of sorting things out.
They watched the city for several days, but the criminal did not appear.
"He's too cautious," Sizhui said. "He won't attack if he senses danger."
Jingyi frowned.

• So he needs bait.
  There was silence.
  Slowly, the three of them looked at Jin Ling.
  “No,” he said immediately.
  “We haven’t said anything yet,” Jingyi replied.
• I know, if you both look at me like that, it won’t lead to anything good!
  Sizhui added calmly:
• Mister Jin, only you are suitable in age and background.
  Jin Ling looked like he was about to argue with fate.
  — Do you want the heir of the Jin clan to wear a woman’s hanfu?
  “For the sake of saving people,” Sizhui said softly.
  Pause.
  — ...I hate it when you use correct arguments.
  In the evening, at the lantern festival, the "daughter of a noble family" appeared.
  She was wearing a beautiful feminine hanfu, her hair was neatly pulled back, and she had beautiful, neat makeup.
  From the outside, no one would have guessed that this was Jin Ling.
  Well... almost no one.
  Because his look still said:
  "Just try to come closer."
  Sizhui and Jingyi watched from afar.
  “He looks convincing,” Sizhui said.
  "Yes," Jingyi agreed. "But I think he'll kill the first person who calls him 'young lady.'"