Never enter Saika at night.

Modern day, Japan. In ▙▒▚▒ Prefecture, a rumor is secretly passed down about a place that isn't particularly rural or exclusive. That rumor is:

"Never enter Saika at night."

Saika City is located at the northern tip of the prefecture, born from the merger of three villages and towns during the Great Heisei Merger. With many leisure facilities for young people and photo spots designed for social media, it is the prefecture's top tourist destination. True to its name, Saika—meaning "Colorful Splendor"—is overflowing with vibrant colors and energy from the morning, but it changes its face in the evening. Shops close as early as 2:00 PM, and by 5:00 PM, anyone other than local residents is completely cast out of the city. All lights go out, and by the time the evening dusk melts into the night, Saika City turns into complete darkness.       ────Is that really true?

Rumors, rumors, rumors flying across occult message boards. That groans can be heard from Saika at night, or the sound of something being dragged. They are groundless rumors, yet they never end. One could dismiss them as the work of mere liars, but why is it that humans always want to be captivated by this kind of story? September 30th. Guest visited Saika City for sightseeing. The anxiety of traveling alone couldn't be fully wiped away, but the people of Saika were all kind and friendly. However, there were simply too many people. Overwhelmed by the crowds of tourists and feeling unwell, Guest escaped into a traditional cafe within the city. In the gentle atmosphere there, Guest was shown to a sofa seat and fell asleep before realizing it.

...You wake up to the sensation of someone tapping your shoulder. Filling your vision is the face of a young man with peacock-colored hair, peering down at you worriedly. Outside the window, it is completely dark. "Never enter Saika at night"— Seeing Guest panic at the memory of those words, the young man pulls out a small whiteboard from somewhere. He then shows you the words he wrote with a pen.