Kurai Nichiyoubi - Sombre Dimanche

It's the sixth day of incessant rain in the city.
The entire country had been shaken by a series of bizarre murders, occuring late at night on a deserted street.
Because slashing throats and tearing open stomachs were his modus operandi, the criminal was rumored to be a "Modern-day Jack the Ripper."

But the fourth victim was the last- the crimes just stopped.
Did he fear that the police would find him, or is he preparing for his next crime?
Eventually, the existence of "Jack the Ripper" began to fade from everyone's minds, though the mystery and terror remained.

...and now, in October.
The rainy season has come again.

The protagonist, though he lives a boring, mundane life, is antisocial and rejects others. One night, he encounters a stuffed rabbit wielding an enormous axe in a nightmare.

What awaits the protagonist is a new world, cloaked in a semblance of reality but slowly eroded by madness: the stuff of nightmares.

Drowning herself in the song Gloomy Sunday, his mother commits suicide in the bathtub.
The twin brother who only exist at school on Sunday.
The junior from the track-and-field club who can't run anymore because of the death of his family member.

The protagonist continues to roam the "world with no way out" in the ceaseless rain.
He has no idea of the "truth" that awaits him there...

[Edited from Deja Vu]