Tantei Kibukawa Ryousuke Jikentan 'Oumagadoki no Kyoushikyoku'

A request came in to the Kibukawa Detective Agency.

The request came from an old acquaintance of Kibukawa, Daidoji Genzo, who wanted the protection of the Daidoji's treasure, "Tokoyo no Watashi", which had received a notice of theft.
Masao Ikurumi and Izuna Sagishima go to the site in Kibukawa's absence.
There, they become involved in a strange incident involving a hidden treasure.
They were investigating the hidden treasure at the Daidoji house.
Then, they find a strange corpse on a snow-covered road on the property.
What is the end of the story played by the dead body that no one knows...?

[From Steam]