Makan no Injou

Gadou Soushin, a man cloaked in an Inverness coat.
He’s a con artist and a skilled demon summoner.
The pursuit of magic is Soushin’s life’s purpose. Maybe that's why a rumor about Boris Doreze’s collection piques his interest one day when Soushin hears of it.
Boris, a well-known collector of occult items, is said to have acquired a rare manuscript related to the original Key of Solomon.
Soushin summons a familiar and heads to the mansion where Boris lives to verify the rumor.

[Translated from dlsite]