Sousoushi to Kizoku Tantei

Shine a light on the hidden truth. One day, Takumyo, who has the special power to "call back souls," receives a request from Seiryuu, a powerful nobleman. Takumyo decides to cooperate for a "certain purpose" related to his own origins, but Seiryuu also has complicated reasons for his actions... (Source: Kadokawa, translated)