Ryougi Shiki:

There was once a renowned painter who built a manor on a secluded plateau. After his passing, a most peculiar incident occurred.
The painter was a man of great wealth, though he never married. He did, however, take in a single foster child.
At the funeral, his relatives and associates gathered, eventually falling into a bitter dispute over the interpretation of his will.
It read: "Within this manor, a painting is hidden. One that brings death to any who look upon it. To the one who finds it, I bequeath half of my estate."
Marvelous, isn't it? A painting that kills upon sight. If it were true, there could be no tale more meaningless.

Fujimaru:

And why is that?

Ryougi Shiki:

Because you would die the moment you saw it, would you not? What purpose would an inheritance serve for the deceased?
Conversely, if one were to lay their eyes upon it and survive, that would mean the painting spoken of in his will laid elsewhere.
Those gathered quickly realized the contradiction. They laughed amongst themselves, sighing at what a difficult man the painter had been.
Until the next morning, when one of the guests was found dead in the manor's storehouse.

Fujimaru:

A murder case?! So the painting that kills upon sight was real?

Ryougi Shiki:

I wonder. To be honest, I was never told the finer details myself.
Among the guests was an architect who had helped build the manor, as well as a detective who had traveled all the way from Tokyo.
I hear that the two of them were commissioned by the painter’s adopted daughter to uncover the truth behind the incident.
If the day ever comes when I can speak of it properly, I shall tell you the rest then.

Fate/Grand Order, Mooncancer Jade Rabbit - Valentine's Scene