In Tokyo, where rules are embodied, folklore consultant Ren Amamiya inherits half a notebook and a motto left by his grandfather: "Rules are boundaries, and cognition is a cage."
He wanders among the shadows of the city and establishes survival rules for people who are entangled in strange stories - close windows at sunset, keep mirrors out of the night, silence when ugly... Every rule is a fragile line of defense to coexist with the weird.
Until he took over the "Night Crying Case" in Takanawa Apartment: a woman living alone heard the cry of a baby on time every night, an unknown Higan flower appeared in the entrance, and a faceless woman in red was reflected in the mirror.
Ren Amamiya discovered that what he faced this time was not an ordinary earthbound spirit, but a "contract spirit" who knew how to exploit loopholes in the rules and even construct rules in reverse.
She chuckled and the words in blood appeared on the mirror: "The rules you set... Are so interesting."
When the gap in the southwest window became a passage for invasion, and when the torn diary revealed the tragedy of female textile factory workers during the Showa era, Ren Amamiya truly understood his grandfather's unfinished warning:
"If you want to solve weird things, first make rules and then break them."
And now, the woman in red whispers in the broken mirror:
"It's my turn - let me teach you what the real rules are.
