Time repeats itself, and the countdown to a world collapse—the number of which is now beyond counting—does not stop. Guest pulled a cold can of coffee from his blazer pocket and took a swig. Seventeen years old. He should be a typical high schooler, worrying about his future career path or stressing over the scope of final exams. But the burden Guest carries is far too heavy. Looking up at the sky, behind the piercing blue, he sees the reflection of pitch-black cracks—the remnants of the "Abyss," the omen of calamity that has swallowed the world time and time again. Of course, in this vast world, Guest is the only human who realizes the fact that the laws of the world are repeatedly collapsing. Crushing the fragments of ruin one by one, he forcibly extends the life of the world. At the end of a salvation that feels like endless, futile labor, he returns once again to the morning commute. Kajiou Town. A town with a somewhat ominous-sounding name, it greets a morning so peaceful it makes one yawn, completely unaware of Guest's life-or-death struggle. The savory scent of bread rises from the shopping district, and the lively laughter of students in uniform echoes from the school route. "...Alright. For now, it's still peaceful." With a mutter, Guest tosses the empty can into a trash bin and lightly readjusts the bag on his shoulder. Another day that no one knows about was beginning quietly for the seventeen-year-old who had postponed the end of the world.

【World Salvation Manual】 ~Suppress the Omen of Calamity: "Abyss"~

【Overview】 The "Abyss" is an omen of calamity threatening the world. If left unchecked, disaster will manifest and the world will face collapse. Execute this manual as instructed to prevent disaster before it happens.

1. 1.
   Signs of Abyss Manifestation (Detection Parameters)

The following abnormal phenomena are confirmed in areas where an Abyss occurs:

・【Visual Abnormality】Enveloping Black Mist Dense black mist generates and floats throughout the target area. ・【Mental Abnormality】Erosion of Human Reason People within the area lose their reason, becoming aggressive and prone to rioting.

2. 2.
   Suppression Procedure (Mission Essentials)

［Step 1］Identify the Manifestation Area Confirm the black mist and the loss of reason in residents to identify the range of influence.

［Step 2］Preparation of the Price To eliminate the omen, the 【Payment of an Appropriate Price】 is indispensable. ※It is impossible to close an Abyss without offering a price.

［Step 3］Execution of the Ritual Offer the price at the center to completely eliminate the omen (black mist and mental degradation).

3. 3.
   Precautions

・Staying inside the black mist for long periods will contaminate the investigator's own reason. ・Failure to pay the price will cause a larger-scale disaster.

3 days until world collapse

And for now, Kajiou Town remains unchanged. Takashi and Kaoru are there as well... The time is 7:32 AM, time for school.