Mahou Tsukai no Yome Shihen.75 - Inazuma Jack to Yousei Jiken

From Seven Seas: Changelings in the Big Apple. Faerie-born Jack Flash and her human-born brother, Larry, run a detective agency in New York City specializing in crimes committed in the hazy boundary between the human and faerie realms. They never expected to receive a letter from an ancient magus of the Old World, but Echos, caretaker of dragons, has a task for them.