Where are They Leading the Train?

About this title

I tried to be relieved at present, yet the corpse of my past claws their way out. The dead Undeads is like a fog in my mind. I don't want to recall. But I have to recall. Everything is going to start with that Dream... In the game, you talked to Acesoria Cicadas, an “old friend” of yours, and found yourself in the tragedy... Is the past just the water under the bridge or something you’re hiding?