The tomb which was painted, being white

This is an original modern battle action story novel.
It is a story of madness and dangerous weapons in the original world-view.

In the nurse disappearance incident, the story began with the discovery of the dead body without a heart.
As you get closer to the truth, the true madness began to surface.
When all was uncovered and done, what do we think about?

[From Dlsite]