About the Hundred Wonders That Occurred in a Certain City

Ariwa Wadachi was an inconspicuous student who kept to the periphery of his class. Possessing psychic abilities that allowed him to see things invisible to others, his daily life was constantly disrupted by inexplicable phenomena.
The one who took an interest in Wadachi was the class's central figure, Rokumiya Kaori. Around the time their interactions began, “numbers” started appearing around Wadachi. First, a 1. Then a 2. Slowly but surely, the numbers grew.
What did these numbers signify? And what lay waiting beyond them...?