Mahoutsukai no Yome Shihen.75: Inazuma Jack to Yousei Jiken

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.

(Source: Seven Seas Entertainment)