Kuroyagi ~Otome-tachi e Sasageru Serenade~

Late 19th century. In a certain place in Western Europe there was a famous house called the Yagi family. Lord Earl was an excellent person as its head.
· · · However, one day the he disappeared. An incident occurred in which all members were found dead. The crime remained unsolved. 100 years have passed since then · · ·
A certain detective tried to bring the truth about this incident up without a request from anyone and vanished without a trace. His best friend is anxious to know about his whereabouts and he steps into the mansion as well. He seems to be a very ordinary journalist, but in reality he has a "witch" as his ancestor.

[From vndbreview]